$ git clone -n https://src.fedoraproject.org/rpms/rust-block-buffer.git /var/lib/mock/f38-build-side-43-rust-devel-1415629-31455/root/chroot_tmpdir/scmroot/rust-block-buffer
Cloning into '/var/lib/mock/f38-build-side-43-rust-devel-1415629-31455/root/chroot_tmpdir/scmroot/rust-block-buffer'...
$ git fetch origin c02e575f8899e965203452974a56a38e82b10847:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-block-buffer
 * [new ref]         c02e575f8899e965203452974a56a38e82b10847 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c02e575 Update to version 0.10.4; Fixes RHBZ#2154940