Git.pm: Use `--includes` when querying insteadOf/pushInsteadOf
The user may have already added KDE's URLs to a separate file and then
included that file in ~/.gitconfig
. Unlike regular git commands,
git config --global
does not process includes without --includes
.
This commit does not change the behavior for adding new options. If the
config options are missing, they are still added to the main
~/.gitconfig
.