Summary:
I always need to remember to exclude it from my patches, and it's the
main reason I don't use phabricator.
It is harmless to anything other than arcanist, so there's no reason to not
check it in, I'd say.
Reviewers: dkl
Reviewed By: dkl
Bug #: 1424257
Differential Revision: https://phabricator.services.mozilla.com/D330
MozReview-Commit-ID: 8uE9ac3uS4y