for example ISBN:1
doesn't become a link, while ISBN:12
(Obviously ISBN numbers are not 1 digit, but custom interwikis like Bug:1 may be)
seen on TWiki version Fri, 31 Mar 2006 build 9626, Plugin API version 1.1
This is true even for 4.0.5
But in current 4.1 code on SVN it seems fixed. It works both here and in my local 4.1 code.
So someone must have seen it and fixed it and not seen this bug item.
So I set it to Waiting For Release so it gets in the release notes