Ensure git_root folder exists

this will actually allow for custom ANSIBLE_INSTALL_ROOT.

Change-Id: I67c5d2c671368b0e645b8ced867fa388fd6c29eb
Closes-Bug: #1647360

playbooks/roles/bifrost-prep-for-install/tasks/main.yml

@@ -13,6 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 ---
+- name: ensure installation root folder exists
+  file:
+    state: directory
+    dest: "{{ git_root }}"
+    owner: "{{ ansible_user_id }}"
+    group: "{{ ansible_user_gid }}"
+
 - name: "Download via GIT"
   include: git_download.yaml
   when: ci_testing_zuul | bool == false and copy_from_local_path | bool == false