The psych we are installing in JRuby has .rb files from the non-Ruby version. Specifically, it is missing the library-loading logic in psych.rb. I suspect it is installing the wrong version, or else the snapshot psych gem we have published does not contain the right .rb files.

@mkristian Can you look into this please?

@tenderlove What do we need to get a jruby psych release finished?