$ git clone -n https://src.fedoraproject.org/rpms/rust-btrd.git /var/lib/mock/f39-build-2261121-54414/root/chroot_tmpdir/scmroot/rust-btrd
Cloning into '/var/lib/mock/f39-build-2261121-54414/root/chroot_tmpdir/scmroot/rust-btrd'...
$ git fetch origin 27e79e58582c2bc2a54ec3283075ee9a98d19d3a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-btrd
 * [new ref]         27e79e58582c2bc2a54ec3283075ee9a98d19d3a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 27e79e5 Update to version 0.5.3; Fixes RHBZ#2245692