FYI this has been accepted as an official bug, issue #1240.

Class ${2:${TM_DIRECTORY/^.+\\/(.*)$/$1/}.$TM_FILENAME_BASE} Extends Ens.Production

Found this in GIT. It evaluates correctly to Test.MyProd on my Mac but to the full filename in the Windows client next to me. Could this be a "backslash \" vs "forward slash /" issue ? My regex knowledge is insufficient here...

Looks a bit like mine :) 

ClassMethod IsValid(s As %String) As %Boolean
{
    f i=1:1:2E6 {
      s s=$REPLACE($ZSTRIP(s,"*E",,"()"),"()","")
    }
    q s=""
}

Since length was more important than speed I put the $ZSTRIP in the loop, and make it run 2M times (3.6M MAXLEN, that should be enough 😂

Sorry I meant to post this under the solution of @Alex Woodhead