[rancid] Trouble automating TFTP downloading using clogin

[ML]

I'm trying to script clogin to login to some switches and pull an IOS 
image via tftp.

clogin -t 300 -c 'copy tftp://1.1.1.1/file.bin flash:' 2.2.2.2

I see the copy command appear to execute on the remote switch but the 
operation ever starts.  I verified with remote tftp server that not a 
single packet ever reaches it.  There is essentially zero output during 
the vty session after the copy starts.  I can successfully execute other 
commands, just not 'copy'.


What could be happening?