For a while I've had the following in my ~/.darcs/defaults:

push --no-set-default --ssh-cm

hoping that it would turn on --ssh-cm.  In fact, it sets the 
"no-set-default" flag to the value "--ssh-cm".  What I really wanted was

push no-set-default
push ssh-cm

Unfortunately I got no warnings from darcs, and it appeared to be working, 
except that I wasn't getting the effect of --ssh-cm, which I only just 
discovered by using 'darcs push --debug'.  I think it would be nice to get 
a helpful warning for people like me who can't be bothered to read the docs :)

Cheers,
	Simon

Ah-hah!  Now I know for sure I'm not the only one.  I think this is a duplicate,
if I'm not mistaken