tests: don't depend on template-created .git/branches

As noted in c8a58ac5a5 (Revert "Don't create the $GIT_DIR/branches
directory on init", 2009-10-31) there was an attempt long ago in
0cc5691a8b (Don't create the $GIT_DIR/branches directory on init,
2009-10-30) to get rid of the legacy "branches" directory.

We should probably get rid of its creation by removing the
"templates/branches--" file. But whatever our default behavior, our
tests should be tightened up to explicitly create the .git/branches
directory if they rely on our default templates, to make the
dependency on those templates clear.

So let's amend the two tests that would fail if .git/branches wasn't
created. To do this introduce a new "TEST_CREATE_REPO_NO_TEMPLATE"
variable, which we'll set before sourcing test-lib.sh, and change the
"git clone" and "git init" commands in the tests themselves to
explicitly pass "--template=".

This way they won't get a .git/branches in either their top-level
.git, or in the ones they create. We can then amend the tests that
rely on the ".git/branches" directory existing to create it
explicitly, and to remove it after its creation.

This new "TEST_CREATE_REPO_NO_TEMPLATE" variable is a less
heavy-handed version of the "NO_SET_GIT_TEMPLATE_DIR" variable. See
a94d305bf8 (t/t0001-init.sh: add test for 'init with init.templatedir
set', 2010-02-26) for its implementation.

Unlike "TEST_CREATE_REPO_NO_TEMPLATE", this new
"TEST_CREATE_REPO_NO_TEMPLATE" variable is narrowly scoped to what the
"git init" in test-lib.sh does, as opposed to the global effect of
"NO_SET_GIT_TEMPLATE_DIR" and the setting of "GIT_TEMPLATE_DIR" in
wrap-for-bin.sh.

I experimented with adding a new "GIT_WRAP_FOR_BIN_VIA_TEST_LIB"
variable set in test-lib.sh, which would cause wrap-for-bin.sh to not
set GIT_TEMPLATE_DIR, GITPERLLIB etc, as we set those in
test-lib.sh. I think that's a viable approach, but it would interact
e.g. with the appending feature of GITPERLLIB added in
8bade1e12e (wrap-for-bin: make bin-wrappers chainable, 2013-07-04).

Doing so would allow us to convert the tests in t0001-init.sh that now
use "NO_SET_GIT_TEMPLATE_DIR" to simply unset "GIT_TEMPLATE_DIR" in a
sub-shell before invoking "git init" or "git clone". I think that
approach is worth pursuing, but let's table it for now. Some future
wrap-for-bin.sh refactoring can try to address it.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t5505-remote.sh

@@ -923,11 +923,12 @@ test_expect_success 'migrate a remote from named file in $GIT_DIR/remotes' '
 '
 
 test_expect_success 'migrate a remote from named file in $GIT_DIR/branches' '
-	git clone one six &&
+	git clone --template= one six &&
 	origin_url=$(pwd)/one &&
 	(
 		cd six &&
 		git remote rm origin &&
+		mkdir .git/branches &&
 		echo "$origin_url#main" >.git/branches/origin &&
 		git remote rename origin origin &&
 		test_path_is_missing .git/branches/origin &&
@@ -938,10 +939,11 @@ test_expect_success 'migrate a remote from named file in $GIT_DIR/branches' '
 '
 
 test_expect_success 'migrate a remote from named file in $GIT_DIR/branches (2)' '
-	git clone one seven &&
+	git clone --template= one seven &&
 	(
 		cd seven &&
 		git remote rm origin &&
+		mkdir .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

@@ -17,6 +17,7 @@ This test checks the following functionality:
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_CREATE_REPO_NO_TEMPLATE=1
 . ./test-lib.sh
 
 D=$(pwd)
@@ -25,7 +26,8 @@ mk_empty () {
 	repo_name="$1"
 	test_when_finished "rm -rf \"$repo_name\"" &&
 	test_path_is_missing "$repo_name" &&
-	git init "$repo_name" &&
+	git init --template= "$repo_name" &&
+	mkdir "$repo_name"/.git/hooks &&
 	git -C "$repo_name" config receive.denyCurrentBranch warn
 }
 
@@ -77,7 +79,7 @@ mk_test_with_hooks() {
 
 mk_child() {
 	test_when_finished "rm -rf \"$2\"" &&
-	git clone "$1" "$2"
+	git clone --template= "$1" "$2"
 }
 
 check_push_result () {
@@ -916,6 +918,7 @@ test_expect_success 'fetch with branches' '
 	mk_empty testrepo &&
 	git branch second $the_first_commit &&
 	git checkout second &&
+	mkdir testrepo/.git/branches &&
 	echo ".." > testrepo/.git/branches/branch1 &&
 	(
 		cd testrepo &&
@@ -929,6 +932,7 @@ test_expect_success 'fetch with branches' '
 
 test_expect_success 'fetch with branches containing #' '
 	mk_empty testrepo &&
+	mkdir testrepo/.git/branches &&
 	echo "..#second" > testrepo/.git/branches/branch2 &&
 	(
 		cd testrepo &&
@@ -943,7 +947,11 @@ test_expect_success 'fetch with branches containing #' '
 test_expect_success 'push with branches' '
 	mk_empty testrepo &&
 	git checkout second &&
+
+	test_when_finished "rm -rf .git/branches" &&
+	mkdir .git/branches &&
 	echo "testrepo" > .git/branches/branch1 &&
+
 	git push branch1 &&
 	(
 		cd testrepo &&
@@ -955,7 +963,11 @@ test_expect_success 'push with branches' '
 
 test_expect_success 'push with branches containing #' '
 	mk_empty testrepo &&
+
+	test_when_finished "rm -rf .git/branches" &&
+	mkdir .git/branches &&
 	echo "testrepo#branch3" > .git/branches/branch2 &&
+
 	git push branch2 &&
 	(
 		cd testrepo &&

t/test-lib.sh

@@ -1528,7 +1528,9 @@ remove_trash_directory "$TRASH_DIRECTORY" || {
 remove_trash=t
 if test -z "$TEST_NO_CREATE_REPO"
 then
-	git init "$TRASH_DIRECTORY" >&3 2>&4 ||
+	git init \
+	    ${TEST_CREATE_REPO_NO_TEMPLATE:+--template=} \
+	    "$TRASH_DIRECTORY" >&3 2>&4 ||
 	error "cannot run git init"
 else
 	mkdir -p "$TRASH_DIRECTORY"