Prior to this patch, the CircleCI continuous integration environment was
configured to report test failures in a negative light, displaying red
cross-marks and reporting that "some checks were not successful" in
commits and GitHub Pull Requests which included them.
The passing/failing status of tests does not influence their
desirability for Test262. (In practice, engines very commonly fail
newly-contributed tests.)
Although these conflicting interpretations does not technically
interfere with the maintainers' ability to merge new contributions, it
does create confusion for many contributors who interpreted the UI as a
rejection of their work.
In addition, this behavior made it impossible to distinguish between the
benign test failures and disruptive infrastructural problems (e.g. the
crashing of engines).
Reconfigure the continuous integration environment to accept passing and
failing tests equally, and to only report a problem when the Test262
project's testing infrastructure behaves unexpectedly.
the double dot gets only commits not in the left side of the double dot.
The right side assumes HEAD.
This will allow us to fetch the correct list of new or modified files in the current branch.