Not only does creating multiple ssh connection make darcs noticeably slower for
some operations, but it has recently been discovered that some firewalls reject
a quick succession of connections from the same source to the same destination,
which means that darcs mysteriously fails if its ssh connections need to pass
through such a firewall.  This explains some previously observed mysterious
failures.

openssh has recently grown a nice ControlMaster feature which might help with this.

Looks easy enough.

I'll just follow this setup here:
http://www.cs.chalmers.se/Cs/Research/Language-technology/darcs/GF/doc/darcs.html

I guess if there is no ssh -M, then darcs will default to the old
non-multiplexing behaviour.

Will unassign if this turns out to be too hard for me.

fixed in 1.0.7 by:
Sat Mar 18 00:33:37 CET 2006  Eric Kow <eric.kow@loria.fr>
  * Multiplex transactions over a single ssh connection (issue32).