py3: stop rewriting xrange() to pycompat.xrange()

We now require the use of pycompat.xrange() in source.

One less feature in the module importer gets us one step closer
to Python 3 native source code.

Differential Revision: https://phab.mercurial-scm.org/D4034

mercurial/__init__.py

@@ -182,7 +182,7 b' if sys.version_info[0] >= 3:'
                     continue
                 r, c = t.start
                 l = (b'; from mercurial.pycompat import '
-                     b'delattr, getattr, hasattr, setattr, xrange, '
+                     b'delattr, getattr, hasattr, setattr, '
                      b'open, unicode\n')
                 for u in tokenize.tokenize(io.BytesIO(l).readline):
                     if u.type in (tokenize.ENCODING, token.ENDMARKER):