If I understand correctly, currently PKGBUILDer can only do a clone, but not a pull. For an update, an existing repository is not reused by doing a pull, but instead one has to use the -c flag to remove the old repository and clone again. It would be great if instead of

==> Cloning the git repository...
==> ERROR: Directory <package> already exists, please run with `-c` to remove it.
  -> skipping package <package>

it would simply do a pull to get the latest version.