Fix rally U-C retrieval from file

At the moment in CI we attempt to fetch U-C for rally from local git
repo. Though rally does fail while attempting to curl the URI
since it does include git patch that is not valid URI in case
if file:// is used.

Change-Id: If2d7732c3816d343cdcea7e7263ea14c37c59f0c

tasks/main.yml

@@ -52,15 +52,34 @@
   uri:
     url: "{{ rally_upper_constraints_url }}"
     return_content: yes
-  register: _u_c_contents
+  register: _u_c_contents_uri
   check_mode: false
+  when: rally_openstack_git_repo is search('http')
+
+- name: Retrieve local filesystem upper constraints in CI
+  command:
+     git --git-dir={{ rally_openstack_git_repo.split('file://')[1] }}/.git show {{ rally_openstack_git_install_branch | default('master') }}:upper-constraints.txt
+  when: rally_openstack_git_repo is search('file://')
+  register: _u_c_contents_git
+  delegate_to: localhost
+  tags:
+    - skip_ansible_lint
+
+- name: Set the constraints content
+  set_fact:
+    _u_c_contents: |-
+      {% if _u_c_contents_uri is not skipped %}
+      {{ _u_c_contents_uri.content }}
+      {% elif _u_c_contents_git is not skipped %}
+      {{ _u_c_contents_git.stdout }}
+      {% endif %}
 
 - name: Install the python venv
   import_role:
     name: "python_venv_build"
   vars:
     venv_python_executable: "{{ rally_venv_python_executable }}"
-    venv_build_constraints: "{{ _u_c_contents.content.split('\n') | reject('match', '^PyYAML=') | list }}"
+    venv_build_constraints: "{{ _u_c_contents.split('\n') | reject('match', '^PyYAML=') | list }}"
     venv_build_global_constraints: "{{ [] }}"
     venv_build_distro_package_list: "{{ rally_devel_distro_packages }}"
     venv_install_destination_path: "{{ rally_bin | dirname }}"