Re: [PATCH] rebase: use reflog to find common base with upstream

[Martin von Zweigbergk <martinvonz@gmail.com>]

On Wed, Oct 16, 2013 at 11:53 AM, John Keeping <john@keeping.me.uk> wrote:
> Commit 15a147e (rebase: use @{upstream} if no upstream specified,
> 2011-02-09) says:
>
>         Make it default to 'git rebase @{upstream}'. That is also what
>         'git pull [--rebase]' defaults to, so it only makes sense that
>         'git rebase' defaults to the same thing.
>
> but that isn't actually the case.  Since commit d44e712 (pull: support
> rebased upstream + fetch + pull --rebase, 2009-07-19), pull has actually
> chosen the most recent reflog entry which is an ancestor of the current
> branch if it can find one.

It is exactly this inconsistency between "git rebase" and "git pull
--rebase" that confused me enough to make me send my first email to
this list almost 4 years ago [1], so thanks for working on this! I
finished that thread with:

  Would it make sense to teach "git rebase" the same tricks as "git
pull --rebase"?

Then it took me a year before I sent a patch not unlike this one [2].
To summarize, the patch did not get accepted then because it makes
rebase a little slower (or a lot slower in some cases). "git pull
--rebase" is of course at least as slow in the same cases, but because
it often involves connecting to a remote host, people would probably
blame the connection rather than git itself even in those rare (?)
cases.

I think

  git merge-base HEAD $(git rev-list -g "$upstream_name")

is roughly correct and hopefully fast enough. That can lead to too
long a command line, so I was planning on teaching merge-base a
--stdin option, but never got around to it.

Martin


[1] http://thread.gmane.org/gmane.comp.version-control.git/136339
[2] http://thread.gmane.org/gmane.comp.version-control.git/166710