This happens when git merge is run to merge multiple commits that are descendants of current HEAD (or are HEAD). We've hit this while updating master to origin/master but accidentaly we called (while being on master): $ git merge master origin/master Here is a minimal testcase: $ git init a $ cd a $ echo a>a $ git commit -minitial $ echo b>a $ git add a $ git commit -msecond $ git checkout master^ $ git merge master master Fast-forwarding to: master Already up-to-date with master Merge made by the 'octopus' strategy. a | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) $ git cat-file commit HEAD tree eebfed94e75e7760540d1485c740902590a00332 parent bd679e85202280b263e20a57639a142fa14c2c64 author Michał Kiedrowicz <michal.kiedrowicz@xxxxxxxxx> 1329132996 +0100 committer Michał Kiedrowicz <michal.kiedrowicz@xxxxxxxxx> 1329132996 +0100 Merge branches 'master' and 'master' into HEAD ... and below is a patch that adds a testcase to Git's testsuite. I would expect `git merge master master` to just 'Fast forward'. Signed-off-by: Michał Kiedrowicz <michal.kiedrowicz@xxxxxxxxx> --- t/t6028-merge-up-to-date.sh | 17 ++++++++++++++++- 1 files changed, 16 insertions(+), 1 deletions(-) diff --git a/t/t6028-merge-up-to-date.sh b/t/t6028-merge-up-to-date.sh index a91644e..824fca5 100755 --- a/t/t6028-merge-up-to-date.sh +++ b/t/t6028-merge-up-to-date.sh @@ -16,7 +16,12 @@ test_expect_success setup ' test_tick && git commit -m second && git tag c1 && - git branch test + git branch test && + echo third >file && + git add file && + test_tick && + git commit -m third && + git tag c2 ' test_expect_success 'merge -s recursive up-to-date' ' @@ -74,4 +79,14 @@ test_expect_success 'merge -s subtree up-to-date' ' ' +test_expect_failure 'merge fast-forward octopus' ' + + git reset --hard c0 && + test_tick && + git merge c1 c2 + expect=$(git rev-parse c2) && + current=$(git rev-parse HEAD) && + test "$expect" = "$current" +' + test_done -- 1.7.9.rc2.155.g2e96 -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html