When the process being exec'ed errors out and outputs a lot of text, shelljs errors out on node 0.12/io.js (i.e. when support for actual execSync is present) on Travis (I'm not able to reproduce this on my Mac).

See this gist: https://gist.github.com/dominykas/f67e139a93fffdeb4c11

See output-mac.txt for the expected case (i.e. git command errors out, dumps quite some text) and see output-travis.txt for the error (Travis build from source)