bug#15310: 24.3.50; [ELPA] Better commit notifications for upstream authors

[Dmitry Gutov <dgutov@yandex.ru>]

Currently, when there are some changes made to a package that has an
upstream, an email gets sent for each group of commits pushed, to
upstream author (or authors, I'm assuming).

When the notification does come, getting the required changes out is not
as easy as it could be.

The commits are all sent together (one notification email per push,
AFAICS), as a plain-text email without attachments.

I have to identify the ones that originated from ELPA, and weren't
synced from upstream, or just sync commits, for each of them copy the
diff to a file manually, and separately copy the message and the author
when making the commit.

Since all paths the such diffs contain "a/packages/<package-name>", I
also have to run a replace command before applying the diff.

Is there a better way to work with these emails?

If no, it would be better if, for example, the script preparing these
emails identified commits not synced from upstream (maybe by file paths
inside the diffs?), fixed the paths, and attached these commits in patch
format that's accepted by 'git am' and already contains the commit
message and author information.