fetch and checkout from git path

Author: Shlomi Noach

script/cibuild-gh-ost-replica-tests

@@ -16,8 +16,11 @@ echo "local commit is:  $local_commit"
 if [ "$remote_commit" != "$local_commit" ] ; then
   rm -rf ./gh-ost-ci-env
   git clone https://github.com/github/gh-ost-ci-env.git
-  git fetch origin real-tar-gz
-  git checkout real-tar-gz
+  (
+    cd gh-ost-ci-env
+    git fetch origin real-tar-gz
+    git checkout real-tar-gz
+  )
 fi
 
 test_mysql_version() {