tools: author_first_release.sh

First version of a simple tool to get a list of the version a user first
contributed to.

Change-Id: I8f1b1fef5343de269c4b6209632c9cedc2cf1a37

tools/author_first_release.sh

+#!/bin/bash
+##
+## List the release each author first contributed to.
+##
+## Usage: author_first_release.sh [TAGS]
+##
+## If the TAGS arguments are unspecified, all tags reported by `git tag`
+## will be considered.
+##
+tags=${@:-$(git tag)}
+for tag in $tags; do
+  git shortlog -n -e -s $tag |
+      cut -f2- |
+      awk "{print \"${tag#v}\t\"\$0}"
+done | sort -k2  | uniq -f2