Add script to rewrite old tags

This is educational mostly, it just shows how the process in rewriting
tags for the issue #72 was done. Since it was an one-off process, this
was not automated completely, we updated old releases manually.

scripts/oneoff/rewrite_old_tags.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+set -o errexit
+set -o pipefail
+
+for old_tag in $(git tag -l | grep '^coffeenet-starter-'); do
+  new_tag=$(echo "${old_tag}" | sed -E -e 's/^coffeenet-starter-(.*)/v\1/')
+  echo "Fixing up tag: ${old_tag} -> ${new_tag}"
+  tag_type=$(git cat-file -t "${old_tag}")
+  if [ $tag_type = "tag" ]; then
+    echo "Annotated tag ${old_tag}, rewriting tag object"
+    new_hash=$(git cat-file -p "${old_tag}" | sed -e "s/^tag .*/tag ${new_tag}/" | git mktag)
+    git update-ref "refs/tags/${new_tag}" $new_hash
+  elif [ $tag_type = "commit" ]; then
+    git tag -f "${new_tag}" "${old_tag}"
+  else
+    echo "ref type for ${old_tag} unknown, dont know what to do"
+  fi
+done