[Mongrel] Upgraded to Ruby 1.9.1 and Mongrel now fails

[Dave Walton]

We recently upgraded to ruby 1.9.1 (in order to get new functions in the
Math module).  We've reinstalled Mongrel with it, and even gone so far to
make some modifications to the compile (based on a post I found on one of
the forums).

Mongrel now fails when we try to launch it:
mongrel_rails cluster::start

With the message:
ERROR RUNNING 'cluster::start': Plugin /cluster::start does not exist in
category /commands
Use help command to get help

Has anyone seen this error?  Is there a known fix?  I saw a posting from a
couple years ago about need to a:
Gem cleanup mongrel_cluster

...but that doesn't appear to have made any difference.

Any suggestions would be greatly appreciated.

Thanks,

Dave