[ WIP ] test(bridge): fix flaky test: TestGithubPushPull

This test periodically fails with the bug_label_change variant, caused
by an unexpected number of operations existing on the bug (typically in
the range of 7-9).

This tree exists to debug it.

NOTE: This tree is built on top of
de7def3f, and should not be merged in
directly. Its parent effectively enables this test to run on CI, which
is used periodically during the iteration of this adventure.

Change-Id: I738207f8cb254b66f3ef18aa525fce39c71060e2