Add debugging.

server.pl

@@ -285,7 +285,9 @@ handle_post(Request) :-
     format(user_error, 'Ref: ~w~n', [Ref]),
     commits(JSON.commits, CommitList),
     list_set(CommitList, modified, ModifiedFileLists),
+    format(user_error, 'Extracted modified file lists: ~w~n', [ModifiedFileLists]),
     union_all(ModifiedFileLists, ModifiedFiles),
+    format(user_error, 'Unified modified files: ~w~n', [ModifiedFiles]),
     list_set(CommitList, message, MessageLists),
     union_all(MessageLists, Messages),
     list_set(CommitList, added, AddedFileLists),