The `-X` prevents that screen is cleared when showing a diff that's
larger than my screen.
I.e. when running `git diff` and press `q`, the last thing I want to see
is the prompt with `git diff` and *not* the part of the diff I browsed,
to be clear
$ git diff
$ <cursor>
Considering that this is somewhat opinionated, I decided to build an
option which allows you to pass arbitrary commands to the less
invocation.
cccd7622bd