remote: fix set-branches when no branches are set

To replace the list of branches to be fetched "git remote set-branches"
first removes the fetch refspecs for the remote and then creates a new
set of fetch refspecs based and the branches passed on the commandline.
When deleting the existing refspecs git_config_set_multivar_gently()
will return a non-zero result if there was nothing to delete.
Unfortunately the calling code treats that as an error and bails out
rather than setting up the new branches. Fix this by not treating a
return value of CONFIG_NOTHING_SET as an error.

Reported-by: Han Jiang <[email protected]>
Signed-off-by: Phillip Wood <[email protected]>

Author: phillipwood

builtin/remote.c

@@ -1567,8 +1567,12 @@ static int update(int argc, const char **argv, const char *prefix)
 
 static int remove_all_fetch_refspecs(const char *key)
 {
-	return git_config_set_multivar_gently(key, NULL, NULL,
-					      CONFIG_FLAGS_MULTI_REPLACE);
+	int res = git_config_set_multivar_gently(key, NULL, NULL,
+						 CONFIG_FLAGS_MULTI_REPLACE);
+	if (res == CONFIG_NOTHING_SET)
+		res = 0;
+
+	return res;
 }
 
 static void add_branches(struct remote *remote, const char **branches,

t/t5505-remote.sh

@@ -1131,7 +1131,9 @@ test_expect_success 'remote set-branches' '
 	+refs/heads/next:refs/remotes/scratch/next
 	+refs/heads/seen:refs/remotes/scratch/seen
 	EOF
-
+	cat  <<-\EOF >expect.replace-missing &&
+	+refs/heads/topic:refs/remotes/scratch/topic
+	EOF
 	git clone .git/ setbranches &&
 	(
 		cd setbranches &&
@@ -1161,14 +1163,20 @@ test_expect_success 'remote set-branches' '
 
 		git remote set-branches --add scratch seen &&
 		git config --get-all remote.scratch.fetch >config-result &&
-		sort <config-result >../actual.respect-ffonly
+		sort <config-result >../actual.respect-ffonly &&
+
+		git config --unset-all remote.scratch.fetch &&
+		git remote set-branches scratch topic &&
+		git config --get-all remote.scratch.fetch \
+					>../actual.replace-missing
 	) &&
 	test_cmp expect.initial actual.initial &&
 	test_cmp expect.add actual.add &&
 	test_cmp expect.replace actual.replace &&
 	test_cmp expect.add-two actual.add-two &&
 	test_cmp expect.setup-ffonly actual.setup-ffonly &&
-	test_cmp expect.respect-ffonly actual.respect-ffonly
+	test_cmp expect.respect-ffonly actual.respect-ffonly &&
+	test_cmp expect.replace-missing actual.replace-missing
 '
 
 test_expect_success 'remote set-branches with --mirror' '