There's really nothing that can be done.  This ties back into #2279, which deserves a proper fix.  I just want to get JRuby loading at this point.  By silently failing and falling back to the old behavior, it's at least no worse than what JRuby users had before, without impacting C users.  But since I had to modify the gemspec dependencies it won't really matter since the gem won't install otherwise.