shx grep -v adds extra newline

Certain uses of grep appear to add extra newlines.

Ex:
Try something like this:

shx ls '~/Music/iTunes' | shx grep 'iTunes'

It acts as expected, producing strings with a single \n for each line.

But

shx ls '~/Music/iTunes' | shx grep '-v' 'iTunes'

appears to add a second newline at the end of the set of strings.

This can be explicitly seen in node:

var sh = require('shelljs')
// terminates with a single newline
sh.ls('~/Music/iTunes').grep('iTunes')
// terminates with two newlines
sh.ls('~/Music/iTunes').grep('-v', 'iTunes')

Reproduce the behavior with the two shx grep command forms in the issue, then compare it with the shown shelljs grep calls. Trace the shx grep entry point and verify that both positive and -v filtering end with only the expected single newline.