$ git clone -n https://src.fedoraproject.org/rpms/rust-serde.git /var/lib/mock/f39-build-1462009-33295/root/chroot_tmpdir/scmroot/rust-serde
Cloning into '/var/lib/mock/f39-build-1462009-33295/root/chroot_tmpdir/scmroot/rust-serde'...
$ git fetch origin 1cb3b14d13099530b8d16a39285dde5ef41288b7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde
 * [new ref]         1cb3b14d13099530b8d16a39285dde5ef41288b7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1cb3b14 Update to version 1.0.189; Fixes RHBZ#2243779