sftp broken on Cygwin?

[John Whitley]

When I wasn't looking, sftp seems to have broken on Cygwin.  At least  
push, pull, and commit have all worked in the past w/ bzr 0.8.2, but  
when I most recently attempted a pull to update a branch on a Cygwin  
installation it failed as:

 >> bzr pull
Using saved location: sftp://user@example.com/~/bzr/repo/a-branch
bzr: ERROR: Invalid url supplied to transport: 'sftp:// 
user at example.com/~/bzr/repo/a-branch': Unsupported protocol: sftp

I can ssh to this host just fine.  I've tried bzr 0.8.2 as well as  
tip of bzr.dev (revno 1809).  Similarly, I've tried paramiko 1.5.4,  
1.6, and tip of trunk.  I suspect that a Cygwin update broke sftp at  
some point.

Is this a known issue?  I started wandering around in the debugger,  
but didn't have time to get very far today.

-- John