digest/bubblebabble module is missing

[chrisseaton]

In MRI, bubblebabble is a separate file, while in JRuby it's in digest.

$ ruby -rdigest/bubblebabble -e "p Digest.bubblebabble 'foo'"
"xinik-zorox"

$ bin/jruby -rdigest/bubblebabble -e "p Digest.bubblebabble 'foo'"
LoadError: no such file to load -- digest/bubblebabble
  require at org/jruby/RubyKernel.java:941
  require at /Users/chrisseaton/Documents/ruby/jruby/lib/ruby/stdlib/rubygems/core_ext/kernel_require.rb:54

$ bin/jruby -rdigest -e "p Digest.bubblebabble 'foo'"
"xinik-zorox"

[kares]

leaving this open as truffle only (due #3246) - although it seems fixed there as well, please confirm.
non-truffle currently loads bubblebabble method on require 'digest' and digest/bubblebabble delegates