Right, and now you can use "git show --pretty=raw" to see the commit header:

    $ git show --pretty=raw 313378458f8c4fb53c808f4b0bae5bf71ba5e23b | head -n 10
    commit 313378458f8c4fb53c808f4b0bae5bf71ba5e23b
    tree 7e93df01bfc9c187d58a0b96e756dd8ac0031c82
    parent e4eef26d985177e4bdd32bf58b6ae40e7ae67289
    author Spencer Creasey <screasey@monetate.com> 1396872901 -0400
    committer Spencer Creasey <screasey@monetate.com> 1396872901 -0400
    lulz 843475
    
        1337 Test Commit
        
        http://lists-archives.com/git/756394-choosing-the-sha1-prefix-of-your-commits.html

There's replies in that thread where the naïve technique I was using was improved a lot.