remote: insert refspecs with no rhs in FETCH_HEAD

When a refspec contains no rhs and thus won't cause an explicit update,
we skip all the logic, but that means that we don't update FETCH_HEAD
with it, which is what the implicit rhs is.

Add another bit of logic which puts those remote heads in the list of
updates so we put them into FETCH_HEAD.

src/remote.c

@@ -1342,9 +1342,20 @@ static int update_tips_for_spec(
 			} else {
 				continue;
 			}
-		} else if (git_refspec_src_matches(spec, head->name) && spec->dst) {
-			if (git_refspec_transform(&refname, spec, head->name) < 0)
-				goto on_error;
+		} else if (git_refspec_src_matches(spec, head->name)) {
+			if (spec->dst) {
+				if (git_refspec_transform(&refname, spec, head->name) < 0)
+					goto on_error;
+			} else {
+				/*
+				 * no rhs mans store it in FETCH_HEAD, even if we don't
+				 update anything else.
+				 */
+				if ((error = git_vector_insert(&update_heads, head)) < 0)
+					goto on_error;
+
+				continue;
+			}
 		} else {
 			continue;
 		}

tests/fetchhead/nonetwork.c

@@ -351,3 +351,47 @@ void test_fetchhead_nonetwork__quote_in_branch_name(void)
 	cl_git_rewritefile("./test1/.git/FETCH_HEAD", FETCH_HEAD_QUOTE_DATA);
 	cl_git_pass(git_repository_fetchhead_foreach(g_repo, read_noop, NULL));
 }
+
+static bool found_master;
+static bool find_master_called;
+
+int find_master(const char *ref_name, const char *remote_url, const git_oid *oid, unsigned int is_merge, void *payload)
+{
+	GIT_UNUSED(remote_url);
+	GIT_UNUSED(oid);
+	GIT_UNUSED(payload);
+
+	find_master_called = true;
+
+	if (!strcmp("refs/heads/master", ref_name)) {
+		cl_assert(is_merge);
+		found_master = true;
+	}
+
+	return 0;
+}
+
+void test_fetchhead_nonetwork__create_when_refpecs_given(void)
+{
+	git_remote *remote;
+	git_buf path = GIT_BUF_INIT;
+	char *refspec = "refs/heads/master";
+	git_strarray specs = {
+		&refspec,
+		1,
+	};
+
+	cl_set_cleanup(&cleanup_repository, "./test1");
+	cl_git_pass(git_repository_init(&g_repo, "./test1", 0));
+
+	cl_git_pass(git_buf_joinpath(&path, git_repository_path(g_repo), "FETCH_HEAD"));
+	cl_git_pass(git_remote_create(&remote, g_repo, "origin", cl_fixture("testrepo.git")));
+
+	cl_assert(!git_path_exists(path.ptr));
+	cl_git_pass(git_remote_fetch(remote, &specs, NULL, NULL));
+	cl_assert(git_path_exists(path.ptr));
+
+	cl_git_pass(git_repository_fetchhead_foreach(g_repo, find_master, NULL));
+	cl_assert(find_master_called);
+	cl_assert(found_master);
+}