$ git clone -n https://src.fedoraproject.org/rpms/rust-libc.git /var/lib/mock/f39-build-1517618-35752/root/chroot_tmpdir/scmroot/rust-libc
Cloning into '/var/lib/mock/f39-build-1517618-35752/root/chroot_tmpdir/scmroot/rust-libc'...
$ git fetch origin 2918ed2c49225dd6638c37a94bdacf751d79698c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-libc
 * [new ref]         2918ed2c49225dd6638c37a94bdacf751d79698c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2918ed2 Update to version 0.2.149; Fixes RHBZ#2242563