class Bundler::URI::RFC2396_Parser

unless +schemes+ is provided. Then it is a Regexp.union with self.pattern[:X_ABS_URI].
Returns Regexp that is default self.regexp[:ABS_URI_REF],

def make_regexp(schemes = nil)
  unless schemes
    @regexp[:ABS_URI_REF]
  else
    /(?=#{Regexp.union(*schemes)}:)#{@pattern[:X_ABS_URI]}/x
  end
end