> This is really a bad mojo on Gems.

I discovered my gem error goes away when I remove one of the require
lines in my irb configure file but I haven't yet figured out what the
specific code that is causing the conflict is.  I'm not even sure what
I should be looking for -- following each and every require in the
whole require tree may get tedious.

>  Nitro 0.23 by chance?

I'm not running Nitro.