mitchellh/vagrant — pull request #4711 by aspiers (2014-10-25 14:06:18+00:00)
Title: eliminate guesswork with Vagrantfile errors

If the `Vagrantfile` has some kind of error, display not only its path and the exception message, but also the originating
line number and exception class.

Also log the full backtrace when the error is in a provider block, just as it is done when it's outside a provider block.