Add patch to merge requests via email
MR !13817 (merged) added basic support of creating MRs from emails but in the email you can only reference an existing branch from which a MR is created. It would be nice to extend this feature so user can send patches directly in the email.
If the email is a patch or has patches in attachments, we create a new branch based on that patch, and then create the MR with the right title and description. If the email is not a patch then the MR is created from the source branch in the subject (current behavior).
In both cases (whether the email is patch or only specifies source branch) the message body is checked for presence of quick actions so user can control target branch, assignee,...
An option would be also to extend quick actions with /source_branch action and allow to specify source branch through quick actions - /source_branch would be allowed only when creating a MR (not for other actions), if used it would have higher priority than message subject.
Applying patches from email is currently not supported neither in Rugged library nor in Gitaly. Basic support is in libgit2 used by Rugged. We will need
git am feature in either Rugged or Gitaly first.
Links / references
Related comments (which this proposal is based on):