Upgrade common submodule

humitos · humitos · commit 56728eb04a73 · 2018-12-17T14:07:14.000+01:00
diff --git a/common b/common
@@ -1 +1 @@
-Subproject commit d8aa79b2b560b8f8d691298fec1912c6c679c8c1
+Subproject commit a6cb6bbafb3cf93bfad7bab98c6636021719cc48
