$ git clone -n https://src.fedoraproject.org/rpms/thunderbird.git /var/lib/mock/f45-build-46526-843/root/chroot_tmpdir/scmroot/thunderbird
Cloning into '/var/lib/mock/f45-build-46526-843/root/chroot_tmpdir/scmroot/thunderbird'...
$ git fetch origin eb62ec4529c9d7bbb42cd7250c2509989b61b47b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/thunderbird
 * [new ref]         eb62ec4529c9d7bbb42cd7250c2509989b61b47b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at eb62ec4 Since we're hitting OOM, require more RAM per cpu