encoding: remove workaround for locale.getpreferredencoding()
locale.getpreferredencoding() was buggy in OS X for Python <2.7.
Since we no longer support Python <2.7, we no longer need this
workaround.
This essentially reverts 2be70ca17311.
# The 9diff extdiff command generates diff(1) compatible output
# suitable for use with the plumber(4).
[extensions]
extdiff =
[extdiff]
9diff = /bin/mercurial/9diff -cm $parent $child $root