util.roles: Return nil if the role has no explicit policy (fixes inheritance) Previously, if the first inherited role had no opinion, it returned false and prevented further consultation of other inherited roles. This bug was found thanks to the implementation of missing test cases identified through mutation testing.

--- a/util/roles.lua	Fri Oct 07 11:35:56 2022 +0100
+++ b/util/roles.lua	Fri Oct 07 16:58:08 2022 +0100
@@ -30,7 +30,7 @@
 				end
 			end
 		end
-		return false;
+		return nil;
 	end
 end