$ git clone -n https://src.fedoraproject.org/rpms/perl-File-Comments.git /var/lib/mock/f45-build-23466-597/root/chroot_tmpdir/scmroot/perl-File-Comments
Cloning into '/var/lib/mock/f45-build-23466-597/root/chroot_tmpdir/scmroot/perl-File-Comments'...
$ git fetch origin b7a2947d4919b389f479aafbfed53f925a7b8883:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-File-Comments
 * [new ref]         b7a2947d4919b389f479aafbfed53f925a7b8883 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b7a2947 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild