Replace virtualenv-tools with a script

virtualenv-tools has a bug which gets triggered in gates: it can't
change the shebang of a virtualenv python bin/ files if they
were generated with a virtualenv script whose shebang ends with
python2 instead of python.

Because we can't modify virtualenv-tools, we use shell scripts
instead.

Change-Id: Ic37abfb14303b93dfc80398d6e37706a68135cb0
Partial-Bug: #1741634
Partial-Bug: #1764470

defaults/main.yml

@@ -278,7 +278,6 @@ monasca_agent_plugins:
 ## Monasca-agent packages that must be installed before anything else
 monasca_agent_requires_pip_packages:
   - virtualenv
-  - virtualenv-tools
   - python-keystoneclient
   - httplib2
 

tasks/monasca_agent_install.yml

@@ -107,7 +107,22 @@
     - ansible_pkg_mgr == 'yum'
     - monasca_agent_get_venv | changed
 
-- name: Update virtualenv path
-  command: >
-    virtualenv-tools --update-path=auto --reinitialize {{ monasca_agent_bin | dirname }}
+# NOTE(odyssey4me):
+# We reinitialize the venv to ensure that the right
+# version of python is in the venv, but we do not
+# want virtualenv to also replace pip, setuptools
+# and wheel so we tell it not to.
+# We do not use --always-copy for CentOS/SuSE due
+# to https://github.com/pypa/virtualenv/issues/565
+- name: Reset virtualenv and update its paths
+  shell: |
+    find {{ monasca_agent_bin }} -name \*.pyc -delete
+    sed -si '1s/^.*python.*$/#!{{ monasca_agent_bin | replace ('/','\/') }}\/python/' {{ monasca_agent_bin }}/*
+    virtualenv {{ monasca_agent_bin | dirname }} \
+        {{ (ansible_pkg_mgr == 'apt') | ternary('--always-copy', '') }} \
+        --no-pip \
+        --no-setuptools \
+        --no-wheel
   when: monasca_agent_get_venv | changed
+  tags:
+    - skip_ansible_lint