rebase: omit patch-identical commits with --fork-point
When the `--fork-point` argument was added to `git rebase`, we changed
the value of $upstream to be the fork point instead of the point from
which we want to rebase. When $orig_head..$upstream is empty this does
not change the behaviour, but when there are new changes in the upstream
we are no longer checking if any of them are patch-identical with
changes in $upstream..$orig_head.
Fix this by introducing a new variable to hold the fork point and using
this to restrict the range as an extra (negative) revision argument so
that the set of desired revisions becomes (in fork-point mode):
git rev-list --cherry-pick --right-only \
$upstream...$orig_head ^$fork_point
This allows us to correctly handle the scenario where we have the
following topology:
C --- D --- E <- dev
/
B <- master@{1}
/
o --- B' --- C* --- D* <- master
where:
- B' is a fixed-up version of B that is not patch-identical with B;
- C* and D* are patch-identical to C and D respectively and conflict
textually if applied in the wrong order;
- E depends textually on D.
The correct result of `git rebase master dev` is that B is identified as
the fork-point of dev and master, so that C, D, E are the commits that
need to be replayed onto master; but C and D are patch-identical with C*
and D* and so can be dropped, so that the end result is:
o --- B' --- C* --- D* --- E <- dev
If the fork-point is not identified, then picking B onto a branch
containing B' results in a conflict and if the patch-identical commits
are not correctly identified then picking C onto a branch containing D
(or equivalently D*) results in a conflict.
This change allows us to handle both of these cases, where previously we
either identified the fork-point (with `--fork-point`) but not the
patch-identical commits *or* (with `--no-fork-point`) identified the
patch-identical commits but not the fact that master had been rewritten.
Reported-by: Ted Felix <ted@tedfelix.com>
Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/git-rebase.sh b/git-rebase.sh
index 06c810b..55da9db 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -59,6 +59,7 @@
To check out the original branch and stop rebasing, run "git rebase --abort".')
"
unset onto
+unset restrict_revision
cmd=
strategy=
strategy_opts=
@@ -546,7 +547,7 @@
"${switch_to:-HEAD}")
if test -n "$new_upstream"
then
- upstream=$new_upstream
+ restrict_revision=$new_upstream
fi
fi
@@ -572,7 +573,7 @@
# and if this is not an interactive rebase.
mb=$(git merge-base "$onto" "$orig_head")
if test "$type" != interactive && test "$upstream" = "$onto" &&
- test "$mb" = "$onto" &&
+ test "$mb" = "$onto" && test -z "$restrict_revision" &&
# linear history?
! (git rev-list --parents "$onto".."$orig_head" | sane_grep " .* ") > /dev/null
then
@@ -626,7 +627,7 @@
then
revisions="$onto..$orig_head"
else
- revisions="$upstream..$orig_head"
+ revisions="${restrict_revision-$upstream}..$orig_head"
fi
run_specific_rebase
