Merge branch 'jk/clone-detached'

* jk/clone-detached:
  clone: always fetch remote HEAD
  make copy_ref globally available
  consider only branches in guess_remote_head
  t: add tests for cloning remotes with detached HEAD

builtin/clone.c

@@ -345,8 +345,9 @@ static void remove_junk_on_signal(int signo)
 static struct ref *wanted_peer_refs(const struct ref *refs,
 		struct refspec *refspec)
 {
-	struct ref *local_refs = NULL;
-	struct ref **tail = &local_refs;
+	struct ref *head = copy_ref(find_ref_by_name(refs, "HEAD"));
+	struct ref *local_refs = head;
+	struct ref **tail = head ? &head->next : &local_refs;
 
 	get_fetch_map(refs, refspec, &tail, 0);
 	if (!option_mirror)
@@ -359,8 +360,11 @@ static void write_remote_refs(const struct ref *local_refs)
 {
 	const struct ref *r;
 
-	for (r = local_refs; r; r = r->next)
+	for (r = local_refs; r; r = r->next) {
+		if (!r->peer_ref)
+			continue;
 		add_extra_ref(r->peer_ref->name, r->old_sha1, 0);
+	}
 
 	pack_refs(PACK_REFS_ALL);
 	clear_extra_refs();

remote.c

@@ -896,7 +896,7 @@ struct ref *alloc_ref(const char *name)
 	return alloc_ref_with_prefix("", 0, name);
 }
 
-static struct ref *copy_ref(const struct ref *ref)
+struct ref *copy_ref(const struct ref *ref)
 {
 	struct ref *cpy;
 	size_t len;
@@ -1667,7 +1667,9 @@ struct ref *guess_remote_head(const struct ref *head,
 
 	/* Look for another ref that points there */
 	for (r = refs; r; r = r->next) {
-		if (r != head && !hashcmp(r->old_sha1, head->old_sha1)) {
+		if (r != head &&
+		    !prefixcmp(r->name, "refs/heads/") &&
+		    !hashcmp(r->old_sha1, head->old_sha1)) {
 			*tail = copy_ref(r);
 			tail = &((*tail)->next);
 			if (!all)

remote.h

@@ -70,7 +70,7 @@ struct refspec {
 extern const struct refspec *tag_refspec;
 
 struct ref *alloc_ref(const char *name);
-
+struct ref *copy_ref(const struct ref *ref);
 struct ref *copy_ref_list(const struct ref *ref);
 
 int check_ref_type(const struct ref *ref, int flags);

t/t5707-clone-detached.sh

@@ -0,0 +1,76 @@
+#!/bin/sh
+
+test_description='test cloning a repository with detached HEAD'
+. ./test-lib.sh
+
+head_is_detached() {
+	git --git-dir=$1/.git rev-parse --verify HEAD &&
+	test_must_fail git --git-dir=$1/.git symbolic-ref HEAD
+}
+
+test_expect_success 'setup' '
+	echo one >file &&
+	git add file &&
+	git commit -m one &&
+	echo two >file &&
+	git commit -a -m two &&
+	git tag two &&
+	echo three >file &&
+	git commit -a -m three
+'
+
+test_expect_success 'clone repo (detached HEAD points to branch)' '
+	git checkout master^0 &&
+	git clone "file://$PWD" detached-branch
+'
+test_expect_success 'cloned HEAD matches' '
+	echo three >expect &&
+	git --git-dir=detached-branch/.git log -1 --format=%s >actual &&
+	test_cmp expect actual
+'
+test_expect_failure 'cloned HEAD is detached' '
+	head_is_detached detached-branch
+'
+
+test_expect_success 'clone repo (detached HEAD points to tag)' '
+	git checkout two^0 &&
+	git clone "file://$PWD" detached-tag
+'
+test_expect_success 'cloned HEAD matches' '
+	echo two >expect &&
+	git --git-dir=detached-tag/.git log -1 --format=%s >actual &&
+	test_cmp expect actual
+'
+test_expect_success 'cloned HEAD is detached' '
+	head_is_detached detached-tag
+'
+
+test_expect_success 'clone repo (detached HEAD points to history)' '
+	git checkout two^ &&
+	git clone "file://$PWD" detached-history
+'
+test_expect_success 'cloned HEAD matches' '
+	echo one >expect &&
+	git --git-dir=detached-history/.git log -1 --format=%s >actual &&
+	test_cmp expect actual
+'
+test_expect_success 'cloned HEAD is detached' '
+	head_is_detached detached-history
+'
+
+test_expect_success 'clone repo (orphan detached HEAD)' '
+	git checkout master^0 &&
+	echo four >file &&
+	git commit -a -m four &&
+	git clone "file://$PWD" detached-orphan
+'
+test_expect_success 'cloned HEAD matches' '
+	echo four >expect &&
+	git --git-dir=detached-orphan/.git log -1 --format=%s >actual &&
+	test_cmp expect actual
+'
+test_expect_success 'cloned HEAD is detached' '
+	head_is_detached detached-orphan
+'
+
+test_done