version: Fixed the CalledProcessError problem

This was due to CalledProcessError not being a built-in error, causing
`raise CalledProcessError` to think the error to be raised was in a
variable called `CalledProcessError`. In some other cases this was due to the constructor of `CalledProcessError` requiring parameters. This commit fixes both.

I could not reproduce this issue on either Python 2.6.8 nor 2.7.3, but I
did reproduce it on 2.6.6 and there are reports of people encountering this
on "some" version of 2.7.