rocky upgrade path broken requirements pecan too low

When upgrading to Rocky we noticed that the pecan requirement is:
pecan!=1.0.2,!=1.0.3,!=1.0.4,!=1.2,>=1.1.1 # BSD

https://github.com/openstack/neutron/blob/stable/rocky/requirements.txt#L11

But when having python2-pecan-1.1.2 which should satisfy this requirement we get below.
After upgrading to python2-pecan-1.3.2 this issue was solved.

2018-09-25 11:03:37.579 416002 INFO neutron.wsgi [-] 172.20.106.11 "GET / HTTP/1.0" status: 500 len: 2523 time: 0.0019162
2018-09-25 11:03:39.582 416002 INFO neutron.wsgi [-] Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/eventlet/wsgi.py", line 490, in handle_one_response
    result = self.application(self.environ, start_response)
  File "/usr/lib/python2.7/site-packages/paste/urlmap.py", line 203, in __call__
    return app(environ, start_response)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 129, in __call__
    resp = self.call_func(req, *args, **kw)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 193, in call_func
    return self.func(req, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/oslo_middleware/base.py", line 131, in __call__
    response = req.get_response(self.application)
  File "/usr/lib/python2.7/site-packages/webob/request.py", line 1313, in send
    application, catch_exc_info=False)
  File "/usr/lib/python2.7/site-packages/webob/request.py", line 1277, in call_application
    app_iter = application(self.environ, start_response)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 129, in __call__
    resp = self.call_func(req, *args, **kw)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 193, in call_func
    return self.func(req, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/oslo_middleware/base.py", line 131, in __call__
    response = req.get_response(self.application)
  File "/usr/lib/python2.7/site-packages/webob/request.py", line 1313, in send
    application, catch_exc_info=False)
  File "/usr/lib/python2.7/site-packages/webob/request.py", line 1277, in call_application
    app_iter = application(self.environ, start_response)
  File "/usr/lib/python2.7/site-packages/pecan/middleware/recursive.py", line 56, in __call__
    return self.application(environ, start_response)
  File "/usr/lib/python2.7/site-packages/pecan/core.py", line 835, in __call__
    return super(Pecan, self).__call__(environ, start_response)
  File "/usr/lib/python2.7/site-packages/pecan/core.py", line 677, in __call__
    controller, args, kwargs = self.find_controller(state)
  File "/usr/lib/python2.7/site-packages/pecan/core.py", line 853, in find_controller
    controller, args, kw = super(Pecan, self).find_controller(_state)
  File "/usr/lib/python2.7/site-packages/pecan/core.py", line 480, in find_controller
    accept.startswith('text/html,') and
AttributeError: 'NoneType' object has no attribute 'startswith'