Create zuul_pip_virtualenv_symlink variable

Expose the ability for a user to create a symlink to a zuul
virtualenv, this is usually needed when you start trying to version
different virtualenv installs.

Change-Id: Icef1ac5c412e6c905c6490899dffa47262812466
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

tasks/install/pip.yaml

@@ -22,3 +22,30 @@
     version: "{{ zuul_pip_version|default(omit) }}"
     virtualenv_python: "{{ zuul_pip_virtualenv_python|default(omit) }}"
     virtualenv: "{{ zuul_pip_virtualenv|default(omit) }}"
+
+- name: Stat zuul_pip_virtualenv_symlink
+  stat:
+    path: "{{ zuul_pip_virtualenv_symlink | dirname }}"
+  register: r
+  no_log: true
+  when: zuul_pip_virtualenv_symlink is defined
+
+- name: Create zuul_pip_virtualenv_symlink directory
+  become: true
+  file:
+    state: directory
+    path: "{{ zuul_pip_virtualenv_symlink | dirname }}"
+  when:
+    - zuul_pip_virtualenv_symlink is defined
+    - not r.stat.exists
+
+- name: Symlink zuul virtualenv
+  become: true
+  file:
+    dest: "{{ zuul_pip_virtualenv_symlink }}"
+    src: "{{ zuul_pip_virtualenv }}"
+    state: link
+  when:
+    - zuul_pip_virtualenv is defined
+    - zuul_pip_virtualenv_symlink is defined
+    - zuul_pip_virtualenv != zuul_pip_virtualenv_symlink