This histogram strategy was introduced in git 1.7.7 (Sept 2011), with the following description (as mentioned by the OP) "git diff" learned a "--histogram" option to use a different diff generation machinery stolen from jgit, which might give better performance. JGit includes src/org/eclipse/jgit/diff/HistogramDiff.java and tst/org/eclipse/jgit/diff/HistogramDiffTest.java The description there is
![What's the difference between `git diff --patience` and `git diff --histogram`?](https://cdn-ak-scissors.b.st-hatena.com/image/square/98d6f053a97a87156775f60757c60865d0f2c47d/height=288;version=1;width=512/https%3A%2F%2Fcdn.sstatic.net%2FSites%2Fstackoverflow%2FImg%2Fapple-touch-icon%402.png%3Fv%3D73d79a89bded)