Discovered while calling a Symfony backed application.

Take the following example:
new PhpExecutable("/path/to/script action --option")

The options are correctly stripped, but the action remains. Leaving the string "/path/to/script action" being passed to PhpExecutableValidator.validateCommand which causes a popup window with the text "file must be a valid file".

If that popup window actually gave the file name, I could have saved myself the hour I wasted tracking down the problem. In fact, a plain old exception would be a lot easier deal with.