Avoid RuntimeException passing bogus "service" parameter to Diffusion commit view
Summary:
PhabricatorRepository::parseRepositoryServicePath() can return null per https://we.phorge.it/source/phorge/browse/master/src/applications/repository/storage/PhabricatorRepository.php;123831b53fb7572cba11e9c990dcb9d247614890$635, thus make the code in DiffusionServeController:getRequestDirectoryPath() at least not crash when handling null and instead fall back to serving a "403 This repository is read-only over HTTP."
There is probably a cleaner approach which I happily leave to any future person willing to figure it out.
Closes T15944
Test Plan: Go to http://phorge.localhost/rABCD0123456789abcdef0123456789abcdef01234567?service=foo
Reviewers: O1 Blessed Committers, 20after4
Reviewed By: O1 Blessed Committers, 20after4
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Maniphest Tasks: T15944
Differential Revision: https://we.phorge.it/D25826