$ git clone -n https://src.fedoraproject.org/rpms/rust-syn0.15.git /var/lib/mock/f40-build-2643784-66490/root/chroot_tmpdir/scmroot/rust-syn0.15
Cloning into '/var/lib/mock/f40-build-2643784-66490/root/chroot_tmpdir/scmroot/rust-syn0.15'...
$ git fetch origin a7c7dcb2408e244b668dcf9a7d6510e7dde3c502:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-syn0.15
 * [new ref]         a7c7dcb2408e244b668dcf9a7d6510e7dde3c502 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a7c7dcb Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild