fix(controller): do not commit to latest

while this was a nice-to-have before, we are actually pushing config
values on top of the latest build, which breaks config:unset.

Author: Matthew Fisher

controller/registry/private.py

@@ -72,8 +72,6 @@ def _commit(repository_path, image, layer, tag):
     cookies = _put_layer(image['id'], layer)
     _put_checksum(image, cookies)
     _put_tag(image['id'], repository_path, tag)
-    # point latest to the new tag
-    _put_tag(image['id'], repository_path, 'latest')
 
 
 def _put_first_image(repository_path):