$ git clone -n https://src.fedoraproject.org/rpms/rust-proc-macro-crate.git /var/lib/mock/f45-build-44015-809/root/chroot_tmpdir/scmroot/rust-proc-macro-crate
Cloning into '/var/lib/mock/f45-build-44015-809/root/chroot_tmpdir/scmroot/rust-proc-macro-crate'...
$ git fetch origin b1853f89c583d87749990ecd04eea4f6b489dc90:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-proc-macro-crate
 * [new ref]         b1853f89c583d87749990ecd04eea4f6b489dc90 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b1853f8 Update to version 3.5.0; Fixes RHBZ#2444368