[PATCH 0 of 3 RFC] Custom 2to3 fixers for hg

[Renato Cunha]

Hello,

this patch series contain the most of my work for the second half of GSoC. They
are:

 - A 2to3-enabled setup.py that allows users to build hg with an automatic
   call to python's refactoring tool;
 - A fixer that converts plain strings to bytes (details in its commit
   message);
 - A "compatibility" module that adds some utility functions to 2to3 and
   monkeypatches os.environ;
 - A fixer that converts b'foo %s' % b'bar', as it won't work in py3k.

Drawbacks of the current approach:

Converting *all* bytestrings is not as good as it seems, since py3k will break
everytime a bytes object is passed where it expected (unicode) strings. Some
calls that fail and I haven't fixed yet:

 * ord will break when fed with something like ord(b'a'[0])
 * os.getcwd will return unicode. Must translate calls to os.getcwdb
 * __slots__ in mdiff must be strings, not bytes
 * there are some inconsistencies that I still don't know how to handle, like
   2to3 will convert "import hgweb.server" to "from . import hgweb.server",
   which breaks in runtime. How to handle that?
 * some other stuff I must have forgotten.

Regards,
Renato Cunha.