Schedule still references a deleted timetable

=====================================
Please fill in steps to reproduce this bug here: was getting back (through dropdown menu) to whole school section of attendance journal from one group, then went awry.
 tis possibly a follow on from #1278240, maybe carrying some old data from 2013..? (I also had issue with timetables looking like they migrated into 2014 year but they were bound by thier established 2013 dates so had to be deleted and reset up as 2014 timetables)
Thanks for building the more current version of the customise attendance journal into this 2.6.1.2.
Thanks also to Tom and Gediminas for their longstanding patience,... I am beginning to learn Linux and hope to be less of a burden in future

=====================================

Exception

TypeError: ('Not enough context information to get parent', <schooltool.timetable.timetable.Timetable object at 0xb0ea62ec>)

Traceback

File "/usr/lib/python2.7/dist-packages/zope/publisher/publish.py", line 132, in publish
  result = publication.callObject(request, obj)
File "/usr/lib/python2.7/dist-packages/zope/app/publication/zopepublication.py", line 207, in callObject
  return mapply(ob, request.getPositionalArguments(), request)
File "/usr/lib/python2.7/dist-packages/zope/publisher/publish.py", line 107, in mapply
  return debug_call(obj, args)
Extra information: schooltool.skin.flourish.zcml_content.FlourishScheduleContainerView_index.html object at 0xafd53d8c
File "/usr/lib/python2.7/dist-packages/zope/publisher/publish.py", line 113, in debug_call
  return obj(*args)
File "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/page.py", line 100, in __call__
  result = self.render(*args, **kw)
File "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/page.py", line 54, in render
  return self.template(*args, **kw)
File "/usr/lib/python2.7/dist-packages/zope/browserpage/viewpagetemplatefile.py", line 83, in __call__
  return self.im_func(im_self, *args, **kw)
File "/usr/lib/python2.7/dist-packages/zope/browserpage/viewpagetemplatefile.py", line 51, in __call__
  sourceAnnotations=getattr(debug_flags, 'sourceAnnotations', 0),
File "/usr/lib/python2.7/dist-packages/zope/pagetemplate/pagetemplate.py", line 132, in pt_render
  strictinsert=0, sourceAnnotations=sourceAnnotations
Template "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/templates/main.pt"
File "/usr/lib/python2.7/dist-packages/zope/pagetemplate/pagetemplate.py", line 240, in __call__
  interpreter()
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 271, in __call__
  self.interpret(self.program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 533, in do_optTag_tal
  self.do_optTag(stuff)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 518, in do_optTag
  return self.no_tag(start, program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 513, in no_tag
  self.interpret(program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 742, in do_insertStructure_tal
  structure = self.engine.evaluateStructure(expr)
File "/usr/lib/python2.7/dist-packages/zope/tales/tales.py", line 696, in evaluate
  return expression(self)
Template "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/templates/main.pt", line 79, column 8
  Expression: PathExpr standard:u'view/page_template|nothing'
File "/usr/lib/python2.7/dist-packages/zope/tales/expressions.py", line 217, in __call__
  return self._eval(econtext)
File "/usr/lib/python2.7/dist-packages/zope/tales/expressions.py", line 211, in _eval
  return ob()
File "/usr/lib/python2.7/dist-packages/zope/browserpage/viewpagetemplatefile.py", line 83, in __call__
  return self.im_func(im_self, *args, **kw)
File "/usr/lib/python2.7/dist-packages/zope/browserpage/viewpagetemplatefile.py", line 51, in __call__
  sourceAnnotations=getattr(debug_flags, 'sourceAnnotations', 0),
File "/usr/lib/python2.7/dist-packages/zope/pagetemplate/pagetemplate.py", line 132, in pt_render
  strictinsert=0, sourceAnnotations=sourceAnnotations
Template "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/templates/page.pt"
File "/usr/lib/python2.7/dist-packages/zope/pagetemplate/pagetemplate.py", line 240, in __call__
  interpreter()
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 271, in __call__
  self.interpret(self.program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 583, in do_setLocal_tal
  self.engine.setLocal(name, self.engine.evaluateValue(expr))
File "/usr/lib/python2.7/dist-packages/zope/tales/tales.py", line 696, in evaluate
  return expression(self)
Template "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/templates/page.pt", line 14, column 2
  Expression: PathExpr standard:u'view/content_template|nothing'
File "/usr/lib/python2.7/dist-packages/zope/tales/expressions.py", line 217, in __call__
  return self._eval(econtext)
File "/usr/lib/python2.7/dist-packages/zope/tales/expressions.py", line 211, in _eval
  return ob()
File "/usr/lib/python2.7/dist-packages/zope/browserpage/viewpagetemplatefile.py", line 83, in __call__
  return self.im_func(im_self, *args, **kw)
File "/usr/lib/python2.7/dist-packages/zope/browserpage/viewpagetemplatefile.py", line 51, in __call__
  sourceAnnotations=getattr(debug_flags, 'sourceAnnotations', 0),
File "/usr/lib/python2.7/dist-packages/zope/pagetemplate/pagetemplate.py", line 132, in pt_render
  strictinsert=0, sourceAnnotations=sourceAnnotations
Template "/usr/lib/python2.7/dist-packages/schooltool/timetable/browser/templates/f_schedule_container_view.pt"
File "/usr/lib/python2.7/dist-packages/zope/pagetemplate/pagetemplate.py", line 240, in __call__
  interpreter()
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 271, in __call__
  self.interpret(self.program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 852, in do_condition
  self.interpret(block)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 533, in do_optTag_tal
  self.do_optTag(stuff)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 518, in do_optTag
  return self.no_tag(start, program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 513, in no_tag
  self.interpret(program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 821, in do_loop_tal
  self.interpret(block)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 533, in do_optTag_tal
  self.do_optTag(stuff)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 518, in do_optTag
  return self.no_tag(start, program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 513, in no_tag
  self.interpret(program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 533, in do_optTag_tal
  self.do_optTag(stuff)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 518, in do_optTag
  return self.no_tag(start, program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 513, in no_tag
  self.interpret(program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 742, in do_insertStructure_tal
  structure = self.engine.evaluateStructure(expr)
File "/usr/lib/python2.7/dist-packages/zope/tales/tales.py", line 696, in evaluate
  return expression(self)
Template "/usr/lib/python2.7/dist-packages/schooltool/timetable/browser/templates/f_schedule_container_view.pt", line 10, column 6
  Expression: PathExpr standard:u'schedule/schooltool:content/boundaries'
File "/usr/lib/python2.7/dist-packages/zope/tales/expressions.py", line 217, in __call__
  return self._eval(econtext)
File "/usr/lib/python2.7/dist-packages/zope/tales/expressions.py", line 211, in _eval
  return ob()
File "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/content.py", line 56, in __call__
  return self.render(*args, **kw)
File "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/zcml_content.py", line 186, in lambda
  setattr(new_class, attr, lambda *a, **kw: method(*a, **kw))
File "/usr/lib/python2.7/dist-packages/zope/browserpage/viewpagetemplatefile.py", line 83, in __call__
  return self.im_func(im_self, *args, **kw)
File "/usr/lib/python2.7/dist-packages/zope/browserpage/viewpagetemplatefile.py", line 51, in __call__
  sourceAnnotations=getattr(debug_flags, 'sourceAnnotations', 0),
File "/usr/lib/python2.7/dist-packages/zope/pagetemplate/pagetemplate.py", line 132, in pt_render
  strictinsert=0, sourceAnnotations=sourceAnnotations
Template "/usr/lib/python2.7/dist-packages/schooltool/timetable/browser/templates/selected_period_date_boundaries.pt"
File "/usr/lib/python2.7/dist-packages/zope/pagetemplate/pagetemplate.py", line 240, in __call__
  interpreter()
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 271, in __call__
  self.interpret(self.program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 533, in do_optTag_tal
  self.do_optTag(stuff)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 518, in do_optTag
  return self.no_tag(start, program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 513, in no_tag
  self.interpret(program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 710, in do_insertTranslation
  self.interpret(stuff[1])
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 652, in do_i18nVariable
  self.interpret(program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 742, in do_insertStructure_tal
  structure = self.engine.evaluateStructure(expr)
File "/usr/lib/python2.7/dist-packages/zope/tales/tales.py", line 696, in evaluate
  return expression(self)
Template "/usr/lib/python2.7/dist-packages/schooltool/timetable/browser/templates/selected_period_date_boundaries.pt", line 3, column 2
  Expression: PathExpr standard:u'context/timetable/schooltool:content/title'
File "/usr/lib/python2.7/dist-packages/zope/tales/expressions.py", line 217, in __call__
  return self._eval(econtext)
File "/usr/lib/python2.7/dist-packages/zope/tales/expressions.py", line 211, in _eval
  return ob()
File "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/content.py", line 56, in __call__
  return self.render(*args, **kw)
File "/usr/lib/python2.7/dist-packages/zope/browserpage/viewpagetemplatefile.py", line 83, in __call__
  return self.im_func(im_self, *args, **kw)
File "/usr/lib/python2.7/dist-packages/schooltool/common/inlinept.py", line 110, in __call__
  showtal=getattr(instance.request.debug, 'showTAL', False),
File "/usr/lib/python2.7/dist-packages/zope/pagetemplate/pagetemplate.py", line 132, in pt_render
  strictinsert=0, sourceAnnotations=sourceAnnotations
File "/usr/lib/python2.7/dist-packages/zope/pagetemplate/pagetemplate.py", line 240, in __call__
  interpreter()
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 271, in __call__
  self.interpret(self.program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 531, in do_optTag_tal
  self.no_tag(stuff[-2], stuff[-1])
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 513, in no_tag
  self.interpret(program)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 343, in interpret
  handlers[opcode](self, args)
File "/usr/lib/python2.7/dist-packages/zope/tal/talinterpreter.py", line 742, in do_insertStructure_tal
  structure = self.engine.evaluateStructure(expr)
File "/usr/lib/python2.7/dist-packages/zope/tales/tales.py", line 696, in evaluate
  return expression(self)
Template "None", line 1, column 0
  Expression: PathExpr standard:'view/title'
File "/usr/lib/python2.7/dist-packages/zope/tales/expressions.py", line 217, in __call__
  return self._eval(econtext)
File "/usr/lib/python2.7/dist-packages/zope/tales/expressions.py", line 194, in _eval
  ob = self._subexprs[-1](econtext)
File "/usr/lib/python2.7/dist-packages/zope/tales/expressions.py", line 124, in _eval
  ob = self._traverser(ob, element, econtext)
File "/usr/lib/python2.7/dist-packages/zope/pagetemplate/engine.py", line 66, in __call__
  request=request)
File "/usr/lib/python2.7/dist-packages/zope/traversing/adapters.py", line 136, in traversePathElement
  return traversable.traverse(nm, further_path)
Extra information: (schooltool.skin.flourish.zcml_content.ContentTitle_title object at 0xafd42dcc, 'title')
File "/usr/lib/python2.7/dist-packages/zope/traversing/adapters.py", line 42, in traverse
  attr = getattr(subject, name, _marker)
Extra information: (schooltool.skin.flourish.zcml_content.ContentTitle_title object at 0xafd42dcc, 'title', [])
File "/usr/lib/python2.7/dist-packages/schooltool/app/browser/app.py", line 1078, in title
  title = getattr(self.context, 'title', __not_set)
File "/usr/lib/python2.7/dist-packages/schooltool/devmode/devmode.py", line 109, in checkPermission
  self, permission, obj)
File "/usr/lib/python2.7/dist-packages/schooltool/securitypolicy/policy.py", line 127, in checkPermission
  perm = self.checkByAdaptation(permission, obj)
File "/usr/lib/python2.7/dist-packages/schooltool/securitypolicy/policy.py", line 136, in checkByAdaptation
  obj = getParent(obj)
File "/usr/lib/python2.7/dist-packages/zope/traversing/api.py", line 135, in getParent
  return location_info.getParent()
File "/usr/lib/python2.7/dist-packages/zope/location/traversing.py", line 192, in getParent
  self.context)

Modules

schooltool 2.6.1.2 (/usr/lib/python2.7/dist-packages)
schooltool.cando 2.6.1 (/usr/lib/python2.7/dist-packages)
schooltool.gradebook 2.6.1 (/usr/lib/python2.7/dist-packages)
schooltool.intervention 2.6.1 (/usr/lib/python2.7/dist-packages)
schooltool.lyceum.journal 2.6.1 (/usr/lib/python2.7/dist-packages)

Runtime

Python 2.7.3 (default, Sep 26 2013, 20:08:41)
[GCC 4.6.3]
Linux ubuntu 3.2.0-58-generic-pae #88-Ubuntu SMP Tue Dec 3 18:00:02 UTC 2013 i686 i686
Filesystem encoding UTF-8, preferred UTF-8