`subprocess.run` does not handle 'None' arguments, so all of our '_for(commit)' functions in our pre-push hooks should return None if the commit argument provided is None.
<rdar://problem/106949161>
Pull request: https://github.com/WebKit/WebKit/pull/11714
Committed 261884@main (98754beb9912): <https://commits.webkit.org/261884@main> Reviewed commits have been landed. Closing PR #11714 and removing active labels.
Committed 259548.450@safari-7615-branch (79f3c6391fc2): <https://commits.webkit.org/259548.450@safari-7615-branch> Reviewed commits have been landed. Closing PR #482 and removing active labels.