$ git clone -n https://src.fedoraproject.org/rpms/bitcoin-core.git /var/lib/mock/f39-build-1585961-38163/root/chroot_tmpdir/scmroot/bitcoin-core
Cloning into '/var/lib/mock/f39-build-1585961-38163/root/chroot_tmpdir/scmroot/bitcoin-core'...
$ git fetch origin 0b830a1469ffb86ce4a02ffb67c3f7cd855f2bb6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/bitcoin-core
 * [new ref]         0b830a1469ffb86ce4a02ffb67c3f7cd855f2bb6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0b830a1 Update README.md