Merge branch 'ds/find-unique-abbrev-optim'

Optimize the code to find shortest unique prefix of object names. * ds/find-unique-abbrev-optim: sha1_name: minimize OID comparisons during disambiguation sha1_name: parse less while finding common prefix sha1_name: unroll len loop in find_unique_abbrev_r() p4211-line-log.sh: add log --online --raw --parents perf test