$ git clone -n https://src.fedoraproject.org/rpms/jakarta-activation.git /var/lib/mock/f39-build-1567816-37600/root/chroot_tmpdir/scmroot/jakarta-activation
Cloning into '/var/lib/mock/f39-build-1567816-37600/root/chroot_tmpdir/scmroot/jakarta-activation'...
$ git fetch origin 8e6d0ee105c077e75614b44c7c12c501eed0d09e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/jakarta-activation
 * [new ref]         8e6d0ee105c077e75614b44c7c12c501eed0d09e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8e6d0ee Set ExclusiveArch on any OS with java_arches