Fix virtualenv-tools issue

please see https://github.com/fireteam/virtualenv-tools/issues/5

This make installation of the virtualenv impossible on CentOS7 since
you endup with python > python2.7 and python2.7 > python

lrwxrwxrwx. 1 root root       9 Nov 24 20:49 python -> python2.7
lrwxrwxrwx. 1 root root       6 Nov 14 20:03 python2 -> python
lrwxrwxrwx. 1 root root       6 Nov 14 20:03 python2.7 -> python

Change-Id: I2377dc89e7220e653c0b9a3aab7e882cf2324f2e
Related-Bug: #1637509
Partial-Bug: #1644629

tasks/glance_install.yml

@@ -100,6 +100,15 @@
   notify:
     - Restart glance services
 
+- name: CentOS remove python from path first
+  file:
+    path:  "{{ glance_bin | dirname }}/bin/python2.7"
+    state: "absent"
+  when:
+    - ansible_pkg_mgr == 'yum'
+    - not glance_developer_mode | bool
+    - glance_get_venv | changed or glance_venv_dir | changed
+
 - name: Update virtualenv path
   command: >
     virtualenv-tools --update-path=auto --reinitialize {{ glance_bin | dirname }}