Fix detecting failed skeleton generator's tests in Python 2
Fix detecting failed skeleton generator's tests in Python 2

Previously we incorrectly considered all tests following a failure as failed,
dumping generator's process output multiple times as a result.

GitOrigin-RevId: 9a2f3a963a93b2e456949957c63ce9cd11d542ce
allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community