plainbox crashes if duplicate test case names are present in the jobs files

Checkbox Build: Installed: 0.15.5+bzr1993+201303181119~quantal1
Plainbox Build: Installed: 0.2+bzr1993+bzr4~quantal1

Distributor ID: Ubuntu
Description: Ubuntu 12.10
Release: 12.10
Codename: quantal

Summary:

In the output below, I am attempting to run plainbox against the cpu testcase "cpu/scaling_test" which is located in /usr/share/checkbox/jobs/cpu.txt

In most cases, plainbox will run against any of the test cases by default in /usr/share/checkbox/jobs. I have found that if custom test cases are added and have a "duplicate" test case name that this error will occur below: See attached test.txt file and note the test case "keys/volume". This test case is already present in "/usr/share/checkbox/jobs/keys.txt"

I spoke with Zyga who mentioned there should be code in plainbox to identify duplicate test cases and handle them properly. Filing a bug as requested by Zyga.

sfeole@sfmadmax:/usr/share/checkbox/jobs$ plainbox run -i 'cpu/scaling_test'
===============================[ Analyzing Jobs ]===============================
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/plainbox/impl/session.py", line 440, in update_desired_job_list
    self._job_list, self._desired_job_list)
  File "/usr/lib/python3/dist-packages/plainbox/impl/depmgr.py", line 163, in resolve_dependencies
    return cls(job_list)._solve(visit_list)
  File "/usr/lib/python3/dist-packages/plainbox/impl/depmgr.py", line 172, in __init__
    self._job_map = self._get_job_map(job_list)
  File "/usr/lib/python3/dist-packages/plainbox/impl/depmgr.py", line 261, in _get_job_map
    raise DependencyDuplicateError(job_map[job.name], job)
plainbox.impl.depmgr.DependencyDuplicateError: duplicate job name: 'keys/volume'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/bin/plainbox", line 9, in <module>
    load_entry_point('plainbox==0.2', 'console_scripts', 'plainbox')()
  File "/usr/lib/python3/dist-packages/plainbox/impl/__init__.py", line 82, in call_impl
    return impl(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/plainbox/impl/box.py", line 112, in main
    retval = box.main(argv)
  File "/usr/lib/python3/dist-packages/plainbox/impl/box.py", line 82, in main
    return ns.command.invoked(ns)
  File "/usr/lib/python3/dist-packages/plainbox/impl/commands/run.py", line 58, in invoked
    return self._run_jobs(ns, job_list, exporter)
  File "/usr/lib/python3/dist-packages/plainbox/impl/commands/run.py", line 137, in _run_jobs
    self._update_desired_job_list(session, matching_job_list)
  File "/usr/lib/python3/dist-packages/plainbox/impl/commands/run.py", line 174, in _update_desired_job_list
    problem_list = session.update_desired_job_list(desired_job_list)
  File "/usr/lib/python3/dist-packages/plainbox/impl/session.py", line 444, in update_desired_job_list
    self._desired_job_list.remove(exc.affected_job)
ValueError: list.remove(x): x not in list

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To Reproduce:

1: Install Checkbox & Plainbox
2: Download the test.txt job file from this bug and place in "/usr/share/checkbox/jobs/"
3: Run plainbox with: plainbox run -i 'cpu/scaling_test'
4: Observe Error