repository wrapper call gitaly for delete_refs with illegal argument

v10.7.0

Import of gitlab projects silently falls with an error ArgumentError: 3:DeleteRefs: empty ExceptWithPrefix and Refs in sidekiq log.

gitaly validation for delete_refs:

	if len(req.ExceptWithPrefix) == 0 && len(req.Refs) == 0 { // You can't delete all refs
		return fmt.Errorf("empty ExceptWithPrefix and Refs")
	}

current wrapper behavior:

      def gitaly_delete_refs(*ref_names)
        gitaly_ref_client.delete_refs(refs: ref_names)
      end

suggest patch:

Index: lib/gitlab/git/repository.rb
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- lib/gitlab/git/repository.rb	(date 1524214574000)
+++ lib/gitlab/git/repository.rb	(date 1524636327324)
@@ -2314,7 +2314,7 @@
       end
 
       def gitaly_delete_refs(*ref_names)
-        gitaly_ref_client.delete_refs(refs: ref_names)
+        gitaly_ref_client.delete_refs(refs: ref_names) if ref_names.any?
       end
 
       def rugged_remove_remote(remote_name)