$ git clone -n https://src.fedoraproject.org/rpms/R-import.git /var/lib/mock/f40-build-1944502-25177/root/chroot_tmpdir/scmroot/R-import
Cloning into '/var/lib/mock/f40-build-1944502-25177/root/chroot_tmpdir/scmroot/R-import'...
$ git fetch origin a3ae86c8fc5f4b0871ad07091f733e8bfcc2456c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-import
 * [new ref]         a3ae86c8fc5f4b0871ad07091f733e8bfcc2456c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a3ae86c R-maint-sig mass rebuild