Henrik Gramner authored Aug 08, 2015 and Anton Mitrofanov committed Aug 19, 2015

Also remove some non-POSIX syntax and improve robustness.

As a bonus the script now runs about 2-3 times faster.

`git rev-list --count` could be used to simplify things even further,
but that functionality was added in git 1.7.2 so keep `wc -l` for now
to maintain compatibility with older git versions.