Checkbox will crash when you try to resume a already-finished session

[Po-Hsu Lin]

After went through all test cases, if you close the GUI without using the exit button but just close it.
The session directory won't be removed.

And if you try to run checkbox again, and select "Rerun last test" or "Continue (set previous test status to PASS)"
it will crash due to there is no next job available, error messages:

ConnectJobReceivers
GuiEngine::ConnectJobReceivers - Done
computed next job -1

I think it will be great if it can bring tester back to the result page.

root@201404-14997:~$ apt-cache policy checkbox
checkbox:
  Installed: 0.17.10+bzr2829+pkg77+legacy1~ubuntu14.04.1
  Candidate: 0.17.10+bzr2829+pkg77+legacy1~ubuntu14.04.1
  Version table:
 *** 0.17.10+bzr2829+pkg77+legacy1~ubuntu14.04.1 0
        500 http://ppa.launchpad.net/checkbox-dev/ppa/ubuntu/ trusty/main amd64 Packages
        100 /var/lib/dpkg/status
     0.17.6-0ubuntu6 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages
root@201404-14997:~$ apt-cache policy plainbox
plainbox:
  Installed: 0.21+bzr3624+pkg25~ubuntu14.04.1
  Candidate: 0.21+bzr3624+pkg25~ubuntu14.04.1
  Version table:
 *** 0.21+bzr3624+pkg25~ubuntu14.04.1 0
        500 http://ppa.launchpad.net/checkbox-dev/ppa/ubuntu/ trusty/main amd64 Packages
        100 /var/lib/dpkg/status
     0.5.3-2 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages
root@201404-14997:~$ plainbox dev list provider
provider '2013.com.canonical.certification:certification-client'
provider '2013.com.canonical.certification:checkbox'
provider '2013.com.canonical.certification:plainbox-resources'

[Zygmunt Krynicki (zyga)]

I ran across this bug while investigating the multiple test result feature. Marking it as confirmed.