Modify example:

- Use bash $'' because it's not specific to git.  It can be used with
  other tools too.
- 0x01 and 0x02 so as not to confuse the issue of NUL in bash strings

git-changelog/demo.sh

@@ -10,7 +10,7 @@ escape-segments() {
import cgi, re, sys

print re.sub(
  r"\x00(.*)\x01", 
  r"\x01(.*)\x02", 
  lambda match: cgi.escape(match.group(1)),
  sys.stdin.read())
'
@@ -30,12 +30,12 @@ EOF

  # - a trick for HTML escaping (avoid XSS): surround %s with unlikely bytes,
  #   \x00 and \x01.  Then pipe Python to escape.
  local format='
  local format=$'
  <tr>
    <td><a href="https://github.com/oilshell/blog-code/commit/%H">%h</a> </td>
    <td class="subject">%x00%s%x01</td>
    <td> <a href="https://github.com/oilshell/blog-code/commit/%H">%h</a> </td>
    <td>\x01%s\x02</td>
  </tr>'
  git log -n 3 --pretty="format:$format" | escape-segments
  git log -n 5 --pretty="format:$format" | escape-segments

  cat <<EOF
    </table>