/usr/bin/git-contrib is in git-extras 1.9.1-2.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 | #!/bin/sh
user="$*"
test -z "$user" && echo "user name required." 1>&2 && exit 1
count=`git log --oneline --pretty="format: %an" | grep "$user" | wc -l`
test $count -eq 0 && echo "$user did not contribute." && exit 1
git shortlog | grep "$user (" -A $count
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