Improve request-pull to handle non-rebased branches
This is actually a few different changes to request-pull,
making it slightly smarter:
1) Minor cleanup of revision->base variable names, making it
follow the head/headrev naming convention that is already
2) Compute the merge-base between the two revisions upfront
and reuse that selected merge-base to create the diffstat.
3) Refuse to generate a pull request for branches that have no
existing relationship. These aren't very common and would mess
up our diffstat generation.
4) Disable the PAGER when running shortlog and diff, as these
would otherwise activate the pager for each command when
git-request-pull is run on a tty. Instead users can get the
entire output paged (if desired) using `git -p request-pull`.
5) Use shortlog rather than `git log | git shortlog` now that
recent shortlog versions are able to run the revision listing
6) Attempt to resolve the input URL using the user's configured
remotes. This is useful if the URL you want the recipient to
see is also the one you used to push your changes. If not a
config-file remote could easily be setup for the public URL
and request-pull could be passed that name instead.
7) Automatically guess and include the remote branch name in the
body of the message. We list the branch name immediately after
the URL, making it easy for the recipient to copy and paste
the entire line onto a `git pull` command line. Rumor has it
Linus likes this format, for exactly that reason.
If multiple branches at the remote match $headrev we take the
first one returned by peek-remote and assume it is suitable.
If no branches are available we warn the user about the problem,
but insert a static string that is not a valid branch name
and would be obvious to anyone reading the message as being
totally incorrect. This allows users to still generate a
template message without network access (for example) and
hand-correct the bits that cannot be verified.
Signed-off-by: Shawn O. Pearce <firstname.lastname@example.org>
Signed-off-by: Junio C Hamano <email@example.com>