$ git clone -n https://src.fedoraproject.org/rpms/rust-circular-buffer.git /var/lib/mock/f45-build-40806-776/root/chroot_tmpdir/scmroot/rust-circular-buffer
Cloning into '/var/lib/mock/f45-build-40806-776/root/chroot_tmpdir/scmroot/rust-circular-buffer'...
$ git fetch origin b082dcb0bfdc94e426339ed089726d068a934fad:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-circular-buffer
 * [new ref]         b082dcb0bfdc94e426339ed089726d068a934fad -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b082dcb Update to version 2.0.1; Fixes RHBZ#2513752