Integrate content caching with existing task logic

Revert the --force flags

use the update id as metric for role caching

Shift the movement of cache to job folder from rsync task to python

Only install roles and collections if needed

Deal with roles and collections for jobs without sync
Skip local copy if roles or collections turned off

update docs for content caching

Design pivot - use empty cache dir to indicate lack of content

Do not cache content if we did not install content

Test changes to allay concerns about reliability of local_path

Do not blow away cache for SCM inventory updates

awx/main/models/projects.py

@@ -423,6 +423,10 @@ class Project(UnifiedJobTemplate, ProjectOptions, ResourceMixin, CustomVirtualEn
                 return True
         return False
 
+    @property
+    def cache_id(self):
+        return str(self.last_job_id)
+
     @property
     def notification_templates(self):
         base_notification_templates = NotificationTemplate.objects
@@ -560,6 +564,19 @@ class ProjectUpdate(UnifiedJob, ProjectOptions, JobNotificationMixin, TaskManage
     def result_stdout_raw(self):
         return self._result_stdout_raw(redact_sensitive=True)
 
+    @property
+    def branch_override(self):
+        """Whether a branch other than the project default is used."""
+        if not self.project:
+            return True
+        return bool(self.scm_branch and self.scm_branch != self.project.scm_branch)
+
+    @property
+    def cache_id(self):
+        if self.branch_override or self.job_type == 'check' or (not self.project):
+            return str(self.id)
+        return self.project.cache_id
+
     def result_stdout_raw_limited(self, start_line=0, end_line=None, redact_sensitive=True):
         return self._result_stdout_raw_limited(start_line, end_line, redact_sensitive=redact_sensitive)
 
@@ -603,9 +620,7 @@ class ProjectUpdate(UnifiedJob, ProjectOptions, JobNotificationMixin, TaskManage
     def save(self, *args, **kwargs):
         added_update_fields = []
         if not self.job_tags:
-            job_tags = ['update_{}'.format(self.scm_type)]
-            job_tags.append('install_roles')
-            job_tags.append('install_collections')
+            job_tags = ['update_{}'.format(self.scm_type), 'install_roles', 'install_collections']
             self.job_tags = ','.join(job_tags)
             added_update_fields.append('job_tags')
         if self.scm_delete_on_update and 'delete' not in self.job_tags and self.job_type == 'check':