It's a bit baffling that git.git suggests using 7-characters commit abbreviations, when they already have collisions for them:

  $ git log --oneline | cut -c 1-7 | sort | uniq -c | grep -v ' 1 '
        2 1536dd9
        2 191f241
        2 2e6e3e8
        2 3b130ad
        2 d53a350