critical:Literal Regexps throws NoMethodError on missing to_s
fails:Literal Regexps does not treat {m,n}+ as possessive
fails:Literal Regexps invokes substitutions for /o only once
fails:Literal Regexps supports /e (EUC encoding)
fails:Literal Regexps supports /u (UTF8 encoding)
fails:Literal Regexps will not clobber capture variables across threads
fails:Literal Regexps does not match ^ after trailing
