Merge pull request #28647 from rallytime/bp-28624

Back-port #28624 to 2015.8

salt/modules/boto_cloudwatch.py

@@ -74,7 +74,7 @@ def __virtual__():
     Only load if boto libraries exist.
     '''
     if not HAS_BOTO:
-        return False
+        return (False, 'The boto_cloudwatch module cannot be loaded: boto libraries are unavailable.')
     __utils__['boto.assign_funcs'](__name__, 'cloudwatch',
                                    module='ec2.cloudwatch')
     return True