Workaround (shell parameter):
To add the "shell" option to the "Nuke (cmdline)", add the following line into the simplecmds/nuke_cmdline.py interface script on the client machines. The SimpleCmds directory can be opened from the QubeGUI under File->Open SimpleCmds directory.
cmdline.add_option( 'shell', 'string',
'Explicitly specify Linux/OSX shell to use when executing the command. (default=/bin/sh)',
label='Shell (Linux/OSX)', choices=['', '/bin/sh', '/bin/bash', '/bin/csh', '/bin/tcsh'])
In addition, we are looking at exposing that parameter to the QubeGUI in a point release.