path: root/t
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authorConrad Irwin <>2011-08-20 21:49:48 (GMT)
committerJunio C Hamano <>2011-08-22 23:00:36 (GMT)
commit55c4a673070f40f2ef12d0be269e95f1df6825a9 (patch)
treef3167659326c1308f6dfe3600ec0b57200cef335 /t
parent1be9d84b2ed18c2b2e2d6a459d2b6d48d5ab86e5 (diff)
Prevent force-updating of the current branch
"git branch -M <foo> <current-branch>" allows updating the current branch which HEAD points, without the necessary house-keeping that git reset normally does to make this operation sensible. It also leaves the reflog in a confusing state (you would be warned when trying to read it). "git checkout -B <current branch> <foo>" is also partly vulnerable to this bug; due to inconsistent pre-flight checks it would perform half of its task and then abort just before rewriting the branch. Again this manifested itself as the index file getting out-of-sync with HEAD. "git branch -f" already guarded against this problem, and aborts with a fatal error. Update "git branch -M", "git checkout -B" and "git branch -f" to share the same check before allowing a branch to be created. These prevent you from updating the current branch. We considered suggesting the use of "git reset" in the failure message but concluded that it was not possible to discern what the user was actually trying to do. Signed-off-by: Conrad Irwin <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 't')
2 files changed, 20 insertions, 0 deletions
diff --git a/t/ b/t/
index a42e039..b66db2b 100755
--- a/t/
+++ b/t/
@@ -180,4 +180,12 @@ test_expect_success 'checkout -b <describe>' '
test_cmp expect actual
+test_expect_success 'checkout -B to the current branch fails before merging' '
+ git checkout branch1 &&
+ setup_dirty_mergeable &&
+ git commit -mfooble &&
+ test_must_fail git checkout -B branch1 initial &&
+ test_must_fail test_dirty_mergeable
diff --git a/t/ b/t/
index 9e69c8c..cb6458d 100755
--- a/t/
+++ b/t/
@@ -98,6 +98,18 @@ test_expect_success 'git branch -m q r/q should fail when r exists' '
test_must_fail git branch -m q r/q
+test_expect_success 'git branch -M foo bar should fail when bar is checked out' '
+ git branch bar &&
+ git checkout -b foo &&
+ test_must_fail git branch -M bar foo
+test_expect_success 'git branch -M baz bam should succeed when baz is checked out' '
+ git checkout -b baz &&
+ git branch bam &&
+ git branch -M baz bam
mv .git/config .git/config-saved
test_expect_success 'git branch -m q q2 without config should succeed' '