Node version (or tell us if you're using electron or some other framework):

4.5.0

ShellJS version (the most recent version/Github branch you see the bug on):

0.7.4

Operating system:

OS X

Description of the bug:

Oddly, 0.7.4 throws internal error when using String options in exec call. For some reason this was working in previous versions, but recent change in 0.7.4 alters the behavior to accept a string option. After changing to the expected signature of object it works as it should. But it's interesting to know why this worked as a string in previous versions? Did a commit from March sneak in to 0.7.4 that altered exec functionality? Or am I missing something in recent commits?

Example ShellJS command to reproduce the error:

var shelljs = require('shelljs');
shelljs.exec('hostname -f', 'silent');