Merge pull request #2391 from bcoca/apt_lock_exception

now catches lock exceptions from apt and returns friendly message

library/apt

@@ -226,6 +226,7 @@ def main():
     p = module.params
     install_recommends = p['install_recommends']
 
+    try:
         cache = apt.Cache()
         if p['default_release']:
             apt_pkg.config['APT::Default-Release'] = p['default_release']
@@ -262,6 +263,9 @@ def main():
         elif p['state'] in [ 'removed', 'absent' ]:
             remove(module, packages, cache, p['purge'])
 
+    except apt.cache.LockFailedException:
+        module.fail_json(msg="Failed to lock apt for exclusive operation")
+
 # this is magic, see lib/ansible/module_common.py
 #<<INCLUDE_ANSIBLE_MODULE_COMMON>>