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

From: Jonathan Nieder <[email-masked]>
Date: Wed, 16 Oct 2013 12:24:13 -0700

Hi,

John Keeping wrote:

>                                    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.
>
> Change rebase so that it uses the same logic.

Nice idea.

Could pull be made to rely on rebase for this as a follow-up?

[...]
> --- a/git-rebase.sh
> +++ b/git-rebase.sh
> @@ -437,6 +437,14 @@ then
>  			error_on_missing_default_upstream "rebase" "rebase" \
>  				"against" "git rebase <branch>"
>  		fi
> +		for reflog in $(git rev-list -g "$upstream_name" 2>/dev/null)
> +		do
> +			if test "$reflog" = "$(git merge-base "$reflog" HEAD)"

"git merge-base --is-ancestor" is faster.

What should happen if HEAD is not a valid commit?  (Tested with:

	$ git checkout --orphan foo
	$ cat >>.git/config <<EOF
	[branch "foo"]
		remote = origin
		merge = refs/heads/master
	EOF
	$ bin-wrappers/git rebase 2>&1 | wc -l
	83

).

diff --git i/git-rebase.sh w/git-rebase.sh
index fd36cf7..d2e2c2e 100755
--- i/git-rebase.sh
+++ w/git-rebase.sh
@@ -439,7 +439,7 @@ then
 		fi
 		for reflog in $(git rev-list -g "$upstream_name" 2>/dev/null)
 		do
-			if test "$reflog" = "$(git merge-base "$reflog" HEAD)"
+			if git merge-base --is-ancestor "$reflog" HEAD
 			then
 				upstream_name=$reflog
 				break