Allow JTs to specify and prompt for SCM branch

Copy project folder each job run
  change cwd to private_data_dir, from proj
  do not add cwd to show_paths if it is
  a subdirectory of private_data_dir, which
  is already shown

Pass the job private_data_dir to the local
  project sync, and also add that directory
  to the project sync show paths

Add GitPython dep and use for job sync logic
  use this to manage shallow clone from desired
  commit, and to map branch to commit,
  and to assess necessity of project sync

Start on some validation change, but not all
  allow arbitrary playbooks with custom branch

awx/playbooks/project_update.yml

@@ -12,8 +12,9 @@
 # scm_password: password (only for svn/insights)
 # scm_accept_hostkey: true/false (only for git, set automatically)
 # scm_revision: current revision in tower
-# scm_revision_output: where to store gathered revision (temporary file)
+# git_refspec: a refspec to fetch in addition to obtaining version
 # roles_enabled: Allow us to pull roles from a requirements.yml file
+# roles_destination: Path to save roles from galaxy to
 # awx_version: Current running version of the awx or tower as a string
 # awx_license_type: "open" for AWX; else presume Tower
 
@@ -29,27 +30,12 @@
       delegate_to: localhost
 
     - block:
-      - name: check repo using git
-        git:
-          dest: "{{project_path|quote}}"
-          repo: "{{scm_url}}"
-          version: "{{scm_branch|quote}}"
-          force: "{{scm_clean}}"
-          update: false
-          clone: false
-        register: repo_check
-        when: scm_full_checkout|default('')
-        ignore_errors: true
-
-      - name: break if already checked out
-        meta: end_play
-        when: scm_full_checkout|default('') and repo_check is succeeded and repo_check.before == scm_branch
-
       - name: update project using git
         git:
           dest: "{{project_path|quote}}"
           repo: "{{scm_url}}"
           version: "{{scm_branch|quote}}"
+          refspec: "{{git_refspec|default(omit)}}"
           force: "{{scm_clean}}"
           accept_hostkey: "{{scm_accept_hostkey|default(omit)}}"
         register: git_result
@@ -131,13 +117,6 @@
       debug: msg="Repository Version {{ scm_version }}"
       when: scm_version is defined
 
-    - name: Write Repository Version
-      copy:
-        dest: "{{ scm_revision_output }}"
-        content: "{{ scm_version }}"
-      when: scm_version is defined and scm_revision_output is defined
-      delegate_to: localhost
-
 - hosts: all
   gather_facts: false
   tasks:
@@ -148,18 +127,12 @@
         register: doesRequirementsExist
 
       - name: fetch galaxy roles from requirements.yml
-        command: ansible-galaxy install -r requirements.yml -p {{project_path|quote}}/roles/
+        command: ansible-galaxy install -r requirements.yml -p {{roles_destination|quote}}
         args:
           chdir: "{{project_path|quote}}/roles"
         register: galaxy_result
-        when: doesRequirementsExist.stat.exists and (scm_version is undefined or (git_result is not skipped and git_result['before'] == git_result['after']))
+        when: doesRequirementsExist.stat.exists
         changed_when: "'was installed successfully' in galaxy_result.stdout"
 
-      - name: fetch galaxy roles from requirements.yml (forced update)
-        command: ansible-galaxy install -r requirements.yml -p {{project_path|quote}}/roles/ --force
-        args:
-          chdir: "{{project_path|quote}}/roles"
-        when: doesRequirementsExist.stat.exists and galaxy_result is skipped
-
       when: roles_enabled|bool
       delegate_to: localhost