t5505/t5516: allow running without .git/branches/ in the templates

When we commit the template directory as part of `make vcxproj`, the
`branches/` directory is not actually commited, as it is empty.

Two tests were not prepared for that situation.

This developer tried to get rid of the support for `.git/branches/` a
long time ago, but that effort did not bear fruit, so the best we can do
is work around in these here tests.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

t/t5505-remote.sh

@@ -1039,7 +1039,7 @@ test_expect_success 'migrate a remote from named file in $GIT_DIR/branches' '
 	(
 		cd six &&
 		git remote rm origin &&
-		mkdir .git/branches &&
+		mkdir -p .git/branches &&
 		echo "$origin_url#main" >.git/branches/origin &&
 		git remote rename origin origin &&
 		test_path_is_missing .git/branches/origin &&
@@ -1054,7 +1054,7 @@ test_expect_success 'migrate a remote from named file in $GIT_DIR/branches (2)'
 	(
 		cd seven &&
 		git remote rm origin &&
-		mkdir .git/branches &&
+		mkdir -p .git/branches &&
 		echo "quux#foom" > .git/branches/origin &&
 		git remote rename origin origin &&
 		test_path_is_missing .git/branches/origin &&

t/t5516-fetch-push.sh

@@ -979,7 +979,7 @@ test_expect_success 'fetch with branches' '
 	mk_empty testrepo &&
 	git branch second $the_first_commit &&
 	git checkout second &&
-	mkdir testrepo/.git/branches &&
+	mkdir -p testrepo/.git/branches &&
 	echo ".." > testrepo/.git/branches/branch1 &&
 	(
 		cd testrepo &&
@@ -993,7 +993,7 @@ test_expect_success 'fetch with branches' '
 
 test_expect_success 'fetch with branches containing #' '
 	mk_empty testrepo &&
-	mkdir testrepo/.git/branches &&
+	mkdir -p testrepo/.git/branches &&
 	echo "..#second" > testrepo/.git/branches/branch2 &&
 	(
 		cd testrepo &&
@@ -1010,7 +1010,7 @@ test_expect_success 'push with branches' '
 	git checkout second &&
 
 	test_when_finished "rm -rf .git/branches" &&
-	mkdir .git/branches &&
+	mkdir -p .git/branches &&
 	echo "testrepo" > .git/branches/branch1 &&
 
 	git push branch1 &&
@@ -1026,7 +1026,7 @@ test_expect_success 'push with branches containing #' '
 	mk_empty testrepo &&
 
 	test_when_finished "rm -rf .git/branches" &&
-	mkdir .git/branches &&
+	mkdir -p .git/branches &&
 	echo "testrepo#branch3" > .git/branches/branch2 &&
 
 	git push branch2 &&