ExpressJS using very out-of-date version of path-to-regexp

In expressjs package.json the version of "path-to-regexp" listed in dependencies is "0.1.7".
This is considerably out-of-date with the the version of "path-to-regexp" in "pillarjs" which is "1.7.0".

Pulling the current "pillarjs" version of "path-to-regexp" into expressjs by upping the version number to
"1.7.0" in expressjs's package.json causes at least one of the expressjs tests to fail (no surprise I guess).

node_modules/path-to-regexp/index.js:394
  return attachKeys(new RegExp('^' + route, flags(options)), keys)
                    ^

SyntaxError: Invalid regular expression: /^\/files\/((?:*))(?:\/(?=$))?$/: Nothing to repeat
    at RegExp (native)

Is there any reason why expressjs is still using the "0.1.7" version of "path-to-regexp" and/or can this
out-of-date version issue be remedied?

Thanks for comments/help, Justin Johansson

[dougwilson]

Hi @indiescripter the upgrade is not backwards-compatible, so it cannot be upgraded until Express 5.0. We are tacking this in numerous issues like #2237 #2057 #2173

I hope this helps!

Ok, understand. Thanks for quick response @dougwilson.

[dougwilson]

No problem! The 0.1.x still receives fixes if necessary, so if you're experiencing a bug in that version, let us know and we can get a fix included :)