Report and patch by Richard Jones.

Reported by David-Sarah Hopwood on the Bitbucket bug tracker of the
former verlib/distutilsversion project.

The goal of the regex is to catch a (alpha), b (beta), c or rc
(release candidate), so the existing pattern puzzled me.  Tests were
OK before and after the change.

Backports:
- sysconfig is now always imported from our backports
- when hashlib is not found, our backport is used instead of the md5
  module (debatable; we could just drop hashlib)

Version-dependent features:
- PEP 370 features are only enabled for 2.6+
- the check for sys.dont_write_bytecode was fixed to use getattr
  with a default value instead of hasattr

Idioms/syntax:
- octal literals lost their extra 0
- misused try/except blocks have been changed back to try/finally
  (it?s legal in 2.4 too, it?s only try/except/finally that isn?t)
- exception catching uses the regular 2.x idiom instead of sys.exc_info
- file objects are closed within finally blocks (this causes much
  whitespace changes but actually makes diff with packaging easier)

Renamed modules:
- some missed renamings (_thread, Queue, isAlive, urllib.urlsplit, etc.)
  were fixed

Other:
- a few false positive replacements of ?packaging? by ?distutils2? in
  comments or docstrings were reverted
- util.is_packaging regained its name
- assorted whitespace/comment/import changes to match packaging

same hash now. This is my understanding of what should happen given the info
at http://docs.python.org/reference/datamodel#object.__hash__

Also added tests for hashing.

Also fixed a nit in a doc string that made emacs colorize versions.py
incorrectly.