Bug 1561737 - Log full exception traceback from android gtest; r=bc

Including the traceback info will include the exception name, like "ADBError" which
should trigger the android-em task retry; it also provides more debugging info.

Differential Revision: https://phabricator.services.mozilla.com/D36116

--HG--
extra : moz-landing-system : lando

testing/gtest/remotegtests.py

@@ -16,6 +16,7 @@ import shutil
 import sys
 import tempfile
 import time
+import traceback
 
 import mozcrash
 import mozdevice
@@ -387,6 +388,7 @@ def main():
         log.info("gtest | Received keyboard interrupt")
     except Exception as e:
         log.error(str(e))
+        traceback.print_exc()
         if isinstance(e, mozdevice.ADBTimeoutError):
             device_exception = True
     finally: