D-Bus testing: better output when a test times out

When a test is stuck in a loop.run() and times out before the expected
event arrives, then the logged message wasn't very informative (just a
generic "timed out"). Now the error message includes a stack backtrace
(useful to find out where the test was waiting, and thus for what) and
the list of all events received so far (useful to determine which one
is missing).

test/test-dbus.py

@@ -35,6 +35,7 @@ from dbus.mainloop.glib import DBusGMainLoop
 import dbus.service
 import gobject
 import sys
+import traceback
 import re
 import atexit
 
@@ -510,7 +511,7 @@ class DBusUtil(Timeout):
         timeout_handle = None
         if timeout and not debugger:
             def timedout():
-                error = "%s timed out after %d seconds" % (self.id(), timeout)
+                error = "%s timed out after %d seconds, current quit events: %s" % (self.id(), timeout, self.quit_events)
                 if Timeout.debugTimeout:
                     print error
                 raise Exception(error)
@@ -518,11 +519,11 @@ class DBusUtil(Timeout):
         try:
             self.running = True
             unittest.TestCase.run(self, result)
-        except KeyboardInterrupt:
+        except KeyboardInterrupt, ex:
             # somehow this happens when timedout() above raises the exception
             # while inside glib main loop
             result.errors.append((self,
-                                  "interrupted by timeout or CTRL-C or Python signal handler problem"))
+                                  "interrupted by timeout (%d seconds, current quit events: %s) or CTRL-C or Python signal handler problem, exception is: %s" % (timeout, self.quit_events, traceback.format_exc())))
         self.running = False
         self.removeTimeout(timeout_handle)
         if debugger: