patch: remove email import workaround for Python 2.4

Python 2.6 provides access to the sub-modules just fine. This workaround
is no longer needed since we no longer support Python 2.4.

mercurial/patch.py

@@ -9,10 +9,6 b''
 import collections
 import cStringIO, email, os, errno, re, posixpath, copy
 import tempfile, zlib, shutil
-# On python2.4 you have to import these by name or they fail to
-# load. This was not a problem on Python 2.7.
-import email.Generator
-import email.Parser
 
 from i18n import _
 from node import hex, short