$ git clone -n https://src.fedoraproject.org/rpms/yarnpkg.git /var/lib/mock/f45-build-46555-846/root/chroot_tmpdir/scmroot/yarnpkg
Cloning into '/var/lib/mock/f45-build-46555-846/root/chroot_tmpdir/scmroot/yarnpkg'...
$ git fetch origin 66282d93a6d406434c70335f0bf0688961ff1117:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/yarnpkg
 * [new ref]         66282d93a6d406434c70335f0bf0688961ff1117 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 66282d9 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild