Autopilot's ProcessSearchError stack trace is unhelpful

[Thomi Richards]

From http://10.97.2.10:8080/job/autopilot-testrunner-otto-saucy/481/testReport/unity8.shell.tests.test_notifications/EphemeralNotificationsTests/test_urgency_order_Desktop_Nexus_4_/

This traceback:

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/unity8/shell/tests/test_notifications.py", line 408, in test_urgency_order
    self.launch_unity()
  File "/usr/lib/python2.7/dist-packages/unity8/shell/tests/__init__.py", line 173, in launch_unity
    **kwargs
  File "/usr/lib/python2.7/dist-packages/autopilot/testcase.py", line 284, in launch_test_application
    dbus_bus
  File "/usr/lib/python2.7/dist-packages/autopilot/introspection/__init__.py", line 188, in get_autopilot_proxy_object_for_process
    dbus_bus=dbus_bus,
  File "/usr/lib/python2.7/dist-packages/autopilot/introspection/__init__.py", line 263, in get_proxy_object_for_existing_process
    process
  File "/usr/lib/python2.7/dist-packages/autopilot/introspection/__init__.py", line 293, in _get_dbus_addresses_from_search_parameters
    % return_code
ProcessSearchError: Process exited with exit code: -5

Needs to be improved. If it exits with a signal (-ve RC), we should print both the numeric, and string values of that signal. We should also print which process this is talking about, and the PID of the exited process.

[PS Jenkins bot (ps-jenkins)]

Fix committed into lp:autopilot/1.3 at revision 348, scheduled for release in autopilot, milestone Unknown