$ git clone -n https://src.fedoraproject.org/rpms/notmuch.git /var/lib/mock/f40-build-735399-106358/root/chroot_tmpdir/scmroot/notmuch
Cloning into '/var/lib/mock/f40-build-735399-106358/root/chroot_tmpdir/scmroot/notmuch'...
$ git fetch origin 48a87dfce67cbcf6afc7f39a54345805b11e1dfd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/notmuch
 * [new ref]         48a87dfce67cbcf6afc7f39a54345805b11e1dfd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 48a87df rebase with upstream release 0.38.1 (rhbz#2241623)