branch -d: base the "already-merged" safety on the branch it merges with

When a branch is marked to merge with another ref (e.g. local 'next' that
merges from and pushes back to origin's 'next', with 'branch.next.merge'
set to 'refs/heads/next'), it makes little sense to base the "branch -d"
safety, whose purpose is not to lose commits that are not merged to other
branches, on the current branch.  It is much more sensible to check if it
is merged with the other branch it merges with.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index d59a9b4aef..e0b760513c 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -468,4 +468,30 @@ test_expect_success 'detect misconfigured autosetuprebase (no value)' '
 	git config --unset branch.autosetuprebase
 '
 
+test_expect_success 'attempt to delete a branch without base and unmerged to HEAD' '
+	git checkout my9 &&
+	git config --unset branch.my8.merge &&
+	test_must_fail git branch -d my8
+'
+
+test_expect_success 'attempt to delete a branch merged to its base' '
+	# we are on my9 which is the initial commit; traditionally
+	# we would not have allowed deleting my8 that is not merged
+	# to my9, but it is set to track master that already has my8
+	git config branch.my8.merge refs/heads/master &&
+	git branch -d my8
+'
+
+test_expect_success 'attempt to delete a branch merged to its base' '
+	git checkout master &&
+	echo Third >>A &&
+	git commit -m "Third commit" A &&
+	git branch -t my10 my9 &&
+	git branch -f my10 HEAD^ &&
+	# we are on master which is at the third commit, and my10
+	# is behind us, so traditionally we would have allowed deleting
+	# it; but my10 is set to track my9 that is further behind.
+	test_must_fail git branch -d my10
+'
+
 test_done