$ git clone -n https://github.com/xcp-ng-rpms/xcp-emu-manager.git /var/lib/mock/v8.3-incoming-9930-28628/root/chroot_tmpdir/scmroot/xcp-emu-manager
Cloning into '/var/lib/mock/v8.3-incoming-9930-28628/root/chroot_tmpdir/scmroot/xcp-emu-manager'...
$ git fetch origin e893fab2571d9298ca3651865e78eee3062ec08b:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xcp-emu-manager
 * [new ref]         e893fab2571d9298ca3651865e78eee3062ec08b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e893fab updated spec + new source