Merge branch 'nd/maint-autofix-tag-in-head' into maint

* nd/maint-autofix-tag-in-head:
  Accept tags in HEAD or MERGE_HEAD
  merge: remove global variable head[]
  merge: use return value of resolve_ref() to determine if HEAD is invalid
  merge: keep stash[] a local variable

Conflicts:
	builtin/merge.c

1 files changed, 12 insertions, 0 deletions

diff --git a/commit.c b/commit.c
index 97b43279c..9f4cc636d 100644
--- a/commit.c
+++ b/commit.c
@@ -39,6 +39,18 @@ struct commit *lookup_commit_reference(const unsigned char *sha1)
 	return lookup_commit_reference_gently(sha1, 0);
 }
 
+struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_name)
+{
+	struct commit *c = lookup_commit_reference(sha1);
+	if (!c)
+		die(_("could not parse %s"), ref_name);
+	if (hashcmp(sha1, c->object.sha1)) {
+		warning(_("%s %s is not a commit!"),
+			ref_name, sha1_to_hex(sha1));
+	}
+	return c;
+}
+
 struct commit *lookup_commit(const unsigned char *sha1)
 {
 	struct object *obj = lookup_object(sha1);