This bug was a Windows-only bug in sencha.exe and is fixed in Cmd 4.0 beta:

http://www.sencha.com/forum/showthre...-Now-Available

http://cdn.sencha.com/cmd/beta/4.0.0...ase-notes.html

That said, if you can't or don't want to use the beta this bug can be corrected by dropping the "sencha.exe" from Cmd v4 in to your Cmd v3.x install folder. This shim did not change much at all except for the error code return.