Merge branch 'jk/refs-df-conflict'

An ancient bug that made Git misbehave with creation/renaming of
refs has been fixed.

* jk/refs-df-conflict:
  refs_resolve_ref_unsafe: handle d/f conflicts for writes
  t3308: create a real ref directory/file conflict

refs.c

@@ -1435,8 +1435,21 @@ const char *refs_resolve_ref_unsafe(struct ref_store *refs,
 		if (refs_read_raw_ref(refs, refname,
 				      sha1, &sb_refname, &read_flags)) {
 			*flags |= read_flags;
-			if (errno != ENOENT || (resolve_flags & RESOLVE_REF_READING))
+
+			/* In reading mode, refs must eventually resolve */
+			if (resolve_flags & RESOLVE_REF_READING)
 				return NULL;
+
+			/*
+			 * Otherwise a missing ref is OK. But the files backend
+			 * may show errors besides ENOENT if there are
+			 * similarly-named refs.
+			 */
+			if (errno != ENOENT &&
+			    errno != EISDIR &&
+			    errno != ENOTDIR)
+				return NULL;
+
 			hashclr(sha1);
 			if (*flags & REF_BAD_NAME)
 				*flags |= REF_ISBROKEN;

t/t1401-symbolic-ref.sh

@@ -129,11 +129,35 @@ test_expect_success 'symbolic-ref does not create ref d/f conflicts' '
 	test_must_fail git symbolic-ref refs/heads/df/conflict refs/heads/df
 '
 
-test_expect_success 'symbolic-ref handles existing pointer to invalid name' '
+test_expect_success 'symbolic-ref can overwrite pointer to invalid name' '
+	test_when_finished reset_to_sane &&
 	head=$(git rev-parse HEAD) &&
 	git symbolic-ref HEAD refs/heads/outer &&
+	test_when_finished "git update-ref -d refs/heads/outer/inner" &&
 	git update-ref refs/heads/outer/inner $head &&
 	git symbolic-ref HEAD refs/heads/unrelated
 '
 
+test_expect_success 'symbolic-ref can resolve d/f name (EISDIR)' '
+	test_when_finished reset_to_sane &&
+	head=$(git rev-parse HEAD) &&
+	git symbolic-ref HEAD refs/heads/outer/inner &&
+	test_when_finished "git update-ref -d refs/heads/outer" &&
+	git update-ref refs/heads/outer $head &&
+	echo refs/heads/outer/inner >expect &&
+	git symbolic-ref HEAD >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'symbolic-ref can resolve d/f name (ENOTDIR)' '
+	test_when_finished reset_to_sane &&
+	head=$(git rev-parse HEAD) &&
+	git symbolic-ref HEAD refs/heads/outer &&
+	test_when_finished "git update-ref -d refs/heads/outer/inner" &&
+	git update-ref refs/heads/outer/inner $head &&
+	echo refs/heads/outer >expect &&
+	git symbolic-ref HEAD >actual &&
+	test_cmp expect actual
+'
+
 test_done

t/t3200-branch.sh

@@ -117,6 +117,16 @@ test_expect_success 'git branch -m bbb should rename checked out branch' '
 	test_cmp expect actual
 '
 
+test_expect_success 'renaming checked out branch works with d/f conflict' '
+	test_when_finished "git branch -D foo/bar || git branch -D foo" &&
+	test_when_finished git checkout master &&
+	git checkout -b foo &&
+	git branch -m foo/bar &&
+	git symbolic-ref HEAD >actual &&
+	echo refs/heads/foo/bar >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'git branch -m o/o o should fail when o/p exists' '
 	git branch o/o &&
 	git branch o/p &&

t/t3308-notes-merge.sh

@@ -79,7 +79,7 @@ test_expect_success 'fail to merge empty notes ref into empty notes ref (z => y)
 test_expect_success 'fail to merge into various non-notes refs' '
 	test_must_fail git -c "core.notesRef=refs/notes" notes merge x &&
 	test_must_fail git -c "core.notesRef=refs/notes/" notes merge x &&
-	mkdir -p .git/refs/notes/dir &&
+	git update-ref refs/notes/dir/foo HEAD &&
 	test_must_fail git -c "core.notesRef=refs/notes/dir" notes merge x &&
 	test_must_fail git -c "core.notesRef=refs/notes/dir/" notes merge x &&
 	test_must_fail git -c "core.notesRef=refs/heads/master" notes merge x &&