hush: Fix assignments being misinterpreted as commands

If there were no variable substitutions in a command, then initial
assignments would be misinterpreted as commands, instead of being skipped
over. This is demonstrated by the following example:

	=> foo=bar echo baz
	Unknown command 'foo=bar' - try 'help'

Signed-off-by: Sean Anderson <seanga2@gmail.com>
2 files changed