tests: respect GIT_TEST_INSTALLED when initializing repositories

It really makes very, very little sense to use a different git
executable than the one the caller indicated via setting the environment
variable GIT_TEST_INSTALLED.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: dscho

t/test-lib-functions.sh

@@ -923,7 +923,8 @@ test_create_repo () {
 	mkdir -p "$repo"
 	(
 		cd "$repo" || error "Cannot setup test environment"
-		"$GIT_EXEC_PATH/git-init" "--template=$GIT_BUILD_DIR/templates/blt/" >&3 2>&4 ||
+		"${GIT_TEST_INSTALLED:-$GIT_EXEC_PATH}/git" init \
+			"--template=$GIT_BUILD_DIR/templates/blt/" >&3 2>&4 ||
 		error "cannot run git init -- have you built things yet?"
 		mv .git/hooks .git/hooks-disabled
 	) || exit