Comment 4 for bug 1297900

Ok, its caused by dialer_app.tests.test_calls.TestCalls.test_incoming

What happens:
* autopilot starts the dialer-app (by system call "/usr/bin/dialer-app --desktop_file_hint=/usr/share/applications/dialer-app.desktop")
* autopilot triggers the incoming call notification and accepts the call
* this causes telephony-service to upstart-app-launch the following url: application:///dialer-app.desktop
* upstart-app-launch doesn't really know about the "manually" launched instance and tries to launch it a second time
* unity8 in turn does reject it because there is already one session for this app

this is not an issue if all instances are launched via upstart-app-launch (hence doesn't happen in real-world scenario)

So I guess the solution is to use upstart-app-launch in dialer-app's autopilot tests.