Merge branch 'jc/avoid-redundant-submodule-fetch'

"git fetch --recurse-submodules" from multiple remotes (either from
a remote group, or "--all") used to make one extra "git fetch" in
the submodules, which has been corrected.

* jc/avoid-redundant-submodule-fetch:
  fetch: do not run a redundant fetch from submodule

builtin/fetch.c

@@ -2188,6 +2188,10 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
 		else if (argc > 1)
 			die(_("fetch --all does not make sense with refspecs"));
 		(void) for_each_remote(get_one_remote_for_fetch, &list);
+
+		/* do not do fetch_multiple() of one */
+		if (list.nr == 1)
+			remote = remote_get(list.items[0].string);
 	} else if (argc == 0) {
 		/* No arguments -- use default remote */
 		remote = remote_get(NULL);
@@ -2262,7 +2266,17 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
 		result = fetch_multiple(&list, max_children);
 	}
 
-	if (!result && (recurse_submodules != RECURSE_SUBMODULES_OFF)) {
+
+	/*
+	 * This is only needed after fetch_one(), which does not fetch
+	 * submodules by itself.
+	 *
+	 * When we fetch from multiple remotes, fetch_multiple() has
+	 * already updated submodules to grab commits necessary for
+	 * the fetched history from each remote, so there is no need
+	 * to fetch submodules from here.
+	 */
+	if (!result && remote && (recurse_submodules != RECURSE_SUBMODULES_OFF)) {
 		struct strvec options = STRVEC_INIT;
 		int max_children = max_jobs;
 

t/t5526-fetch-submodules.sh

@@ -1125,4 +1125,31 @@ test_expect_success 'fetch --recurse-submodules updates name-conflicted, unpopul
 	)
 '
 
+test_expect_success 'fetch --all with --recurse-submodules' '
+	test_when_finished "rm -fr src_clone" &&
+	git clone --recurse-submodules src src_clone &&
+	(
+		cd src_clone &&
+		git config submodule.recurse true &&
+		git config fetch.parallel 0 &&
+		git fetch --all 2>../fetch-log
+	) &&
+	grep "^Fetching submodule sub$" fetch-log >fetch-subs &&
+	test_line_count = 1 fetch-subs
+'
+
+test_expect_success 'fetch --all with --recurse-submodules with multiple' '
+	test_when_finished "rm -fr src_clone" &&
+	git clone --recurse-submodules src src_clone &&
+	(
+		cd src_clone &&
+		git remote add secondary ../src &&
+		git config submodule.recurse true &&
+		git config fetch.parallel 0 &&
+		git fetch --all 2>../fetch-log
+	) &&
+	grep "Fetching submodule sub" fetch-log >fetch-subs &&
+	test_line_count = 2 fetch-subs
+'
+
 test_done