Reported with patch at TWiki:Support/UserWikiNameI18N
Note that this patch is potentially very dangerous
. The filter-in expression only accepted a limited range of characters. By rewriting to a filter out
expression there is an risk that an "active" character might be missed. This could be especially dangerous on a server platform that doesn't support safe pipes, such as Windows.
Filtering is not actually required on the safe platforms. So I have changed the code to apply the existing aggressive filtering-in only on unsafe platforms. if someone wants to use I18N
usernames on an unsafe platform, then they will have to change the %USERNAME|S% specs to %USERNAME|U% and accept the associated risk.