facebook/hhvm — pull request #1979 by idn2104 (2014-03-04 06:26:37+00:00)
Title: Make escapeshellarg(<empty>) return "''" in non-HH mode.

https://github.com/facebook/hhvm/issues/1789

If not in hip hop syntax mode, return ```''``` when escapeshellarg is called on empty string for compatibility with zend. Otherwise, leave output unchanged.