fix tagging with tip

NEWS.rst

@@ -2,6 +2,11 @@
 History
 =======
 
+16.8.1
+------
+
+Stop tagging with tip.
+
 16.8.0
 ------
 

odoo_scripts/docker_build.py

@@ -215,8 +215,9 @@
         call(["rm", dockerfile])
     # retag
     for tag in tags:
-        _logger.info("Docker with tag %s", tag)
-        docker_client.images.get(repository).tag(repository, tag=tag)
+        if tag != "tip":
+            _logger.info("Docker with tag %s", tag)
+            docker_client.images.get(repository).tag(repository, tag=tag)
 
     if push:
         _logger.info("Docker push %s", repository)