`comments_pagename` is `comment_` so the above code needs a comment page to contain
two underscores. I think that is the root of the bug. --[[Joey]]
+
+> Removed the trailing underscore in the regexp, so it should be fixed,
+> though I have not tested the fix. Leaving this bug open until it's
+> confirmed fixed. (I deployed it to branchable.)
+>
+> This will only fix the stored permalink metadata for a comment when its get
+> preprocessed again, not immediately. That's ok for notifyemail,
+> but other uses of permalink might need a wiki rebuild to get the bug fix.
+> --[[Joey]]
+>
+>> I'm not sure that I see how the regexp was wrong? It's looking for,
+>> for example,
+>>
+>> foo/comment_1_eaab671848ee6129f6fe9399474eeac0._comment
+>> sccccccccdu
+>>
+>> where
+>>
+>> * *s* marks the literal `/`
+>> * *cccc* marks `comments_pagename`
+>> * *d* marks `\d+` (one or more digits)
+>> * *u* marks the literal `_`
+>>
+>> The old regexp would have failed for the older format
+>> `foo/comment_1._comment`, though.
+>>
+>> --[[smcv]]