I asked a question.
The user D.W. answered. Then I found a bug in his answer. Then I commented that I apparently know how to fix the bug (without thorough rewriting everything).
But then D.W. deleted his answer. He probably haven't read my next comment carefully.
As such I propose to allow the questioner to view deleted answers to his question, for situations like this, so that the questioner could be able to contact the answerer even if the answer is deleted.
Fortunately I have restored the deleted answer from Google cache: https://en.wikiversity.org/wiki/Automatic_transformation_of_XML_namespaces/Implementation/Precedences/Old_answer
That I need to use Google cache indicates a problem. It should be solved within StackExchange, without resorting to hacks like Google cache.