Make 'got clone -b' work for repositories which lack a HEAD reference
that points to an existing branch.

Regression test which reproduces the problem is included.

Patch fixes this error:
  got-fetch-pack: could not find any branches to fetch

Also ensures that default config files get created in this case.

ok?
 
diff ca7cfae029f0cbca1f65f326025744f627b69d92 593af7bd3baeb8314b7ef9a11fe0559a6ba9557d
commit - ca7cfae029f0cbca1f65f326025744f627b69d92
commit + 593af7bd3baeb8314b7ef9a11fe0559a6ba9557d
blob - c0c38ea47dfbd657ee0c14d0e8829767ad691ae6
blob + 1e29e64a3d1e97b5787efdf1754a70fe1615d190
--- got/got.c
+++ got/got.c
@@ -1856,6 +1856,7 @@ cmd_clone(int argc, char *argv[])
 			goto done;
 	}
 	if (pe == NULL) {
+		struct got_reference *target_ref = NULL;
 		/*
 		 * We failed to set the HEAD reference. If we asked for
 		 * a set of wanted branches use the first of one of those
@@ -1863,12 +1864,12 @@ cmd_clone(int argc, char *argv[])
 		 */
 		TAILQ_FOREACH(pe, &wanted_branches, entry) {
 			const char *target = pe->path;
-			struct got_reference *target_ref;
 
 			error = got_ref_open(&target_ref, repo, target, 0);
 			if (error) {
 				if (error->code == GOT_ERR_NOT_REF) {
 					error = NULL;
+					target_ref = NULL;
 					continue;
 				}
 				goto done;
@@ -1881,6 +1882,20 @@ cmd_clone(int argc, char *argv[])
 				goto done;
 			break;
 		}
+
+		if (!fpa.configs_created && target_ref) {
+			error = create_config_files(fpa.config_info.proto,
+			    fpa.config_info.host, fpa.config_info.port,
+			    fpa.config_info.remote_repo_path,
+			    fpa.config_info.git_url,
+			    fpa.config_info.fetch_all_branches,
+			    fpa.config_info.mirror_references,
+			    fpa.config_info.symrefs,
+			    fpa.config_info.wanted_branches,
+			    fpa.config_info.wanted_refs, fpa.repo);
+			if (error)
+				goto done;
+		}
 	}
 
 	if (verbosity >= 0)
blob - 6cac7e61e2407f2c053f4cf8256c67ae466489a6
blob + 4fa55782d6cfa72a92ffedfb310e3ac0e508e55c
--- libexec/got-fetch-pack/got-fetch-pack.c
+++ libexec/got-fetch-pack/got-fetch-pack.c
@@ -373,7 +373,8 @@ fetch_pack(int fd, int packfd, uint8_t *pack_sha1,
 					break;
 				}
 			}
-			continue;
+			if (default_branch)
+				continue;
 		}
 		if (strstr(refname, "^{}")) {
 			if (chattygot) {
blob - 35d7c0ba41e646078b5beea834a05d4d28891363
blob + 58ef8f4044adf772026d09c3bfc6ee1dc2e947ef
--- regress/cmdline/clone.sh
+++ regress/cmdline/clone.sh
@@ -754,6 +754,79 @@ test_parseargs "$@"
 	test_done "$testroot" "$ret"
 }
 
+test_clone_dangling_headref() {
+	local testroot=`test_init clone_dangling_headref`
+	local testurl=ssh://127.0.0.1/$testroot
+	local commit_id=`git_show_head $testroot/repo`
+
+	got branch -r $testroot/repo -d master > /dev/null
+	got branch -r $testroot/repo -c $commit_id foo
+
+	got ref -l -r $testroot/repo > $testroot/stdout
+
+	echo "HEAD: refs/heads/master" > $testroot/stdout.expected
+	echo "refs/heads/foo: $commit_id" >> $testroot/stdout.expected
+	# refs/heads/master is missing because it was deleted above
+
+	cmp -s $testroot/stdout $testroot/stdout.expected
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		diff -u $testroot/stdout.expected $testroot/stdout
+		test_done "$testroot" "$ret"
+		return 1
+	fi
+
+	got clone -q -b foo $testurl/repo $testroot/repo-clone
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		echo "got clone command failed unexpectedly" >&2
+		test_done "$testroot" "$ret"
+		return 1
+	fi
+
+	got ref -l -r $testroot/repo-clone > $testroot/stdout
+
+	echo "HEAD: refs/heads/master" > $testroot/stdout.expected
+	echo "refs/heads/foo: $commit_id" >> $testroot/stdout.expected
+	echo "refs/remotes/origin/foo: $commit_id" >> $testroot/stdout.expected
+
+	cat > $testroot/got.conf.expected <<EOF
+remote "origin" {
+	server 127.0.0.1
+	protocol ssh
+	repository "$testroot/repo"
+	branch { "foo" }
+}
+EOF
+	cmp -s $testroot/repo-clone/got.conf $testroot/got.conf.expected
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		diff -u $testroot/got.conf.expected \
+			$testroot/repo-clone/got.conf
+		test_done "$testroot" "$ret"
+		return 1
+	fi
+
+	cat > $testroot/config.expected <<EOF
+[core]
+	repositoryformatversion = 0
+	filemode = true
+	bare = true
+
+[remote "origin"]
+	url = ssh://127.0.0.1$testroot/repo
+	fetch = refs/heads/foo:refs/remotes/origin/foo
+	fetch = refs/tags/*:refs/tags/*
+EOF
+	cmp -s $testroot/repo-clone/config $testroot/config.expected
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		diff -u $testroot/config.expected \
+			$testroot/repo-clone/config
+	fi
+	test_done "$testroot" "$ret"
+}
+
 test_parseargs "$@"
 run_test test_clone_basic
 run_test test_clone_list
@@ -765,3 +838,4 @@ run_test test_clone_multiple_branches
 run_test test_clone_branch_and_reference
 run_test test_clone_reference_mirror
 run_test test_clone_multiple_branches
+run_test test_clone_dangling_headref