module Sprockets::DigestUtils

def pack_urlsafe_base64digest(bin)

Returns urlsafe base64 String.

bin - String bytes

Internal: Pack a binary digest to a urlsafe base64 encoded string. 
def pack_urlsafe_base64digest(bin)
  str = pack_base64digest(bin)
  str.tr!('+/'.freeze, '-_'.freeze)
  str.tr!('='.freeze, ''.freeze)
  str
end