You're the man, Marton! Consider the bounty won!

Marton found a bug in Mechanize's #to_absolute_uri method caused by
the use of #zip which caused already-escaped characters beyond the
first to be dropped. He replaced it with some SyncEnumerator hackery.
I'll let the Aaron Patterson know about the fix to Mechanize.

Good job Marton. We (and Blackbook and probably Mechanize, too)
appreciate your genius (and tolerance level for reading through that
nasty bit of Javascript to highlight the problem).

Dave