Backport PEP 3141 from the py3k branch to the trunk. This includes r50877 (just
the complex_pow part), r56649, r56652, r56715, r57296, r57302, r57359, r57361,
r57372, r57738, r57739, r58017, r58039, r58040, and r59390, and new
documentation. The only significant difference is that round(x) returns a float
to preserve backward-compatibility. See http://bugs.python.org/issue1689.
diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst
index ea2bb1a..9c416f8 100644
--- a/Doc/reference/expressions.rst
+++ b/Doc/reference/expressions.rst
@@ -801,7 +801,8 @@
raised).
Raising ``0.0`` to a negative power results in a :exc:`ZeroDivisionError`.
-Raising a negative number to a fractional power results in a :exc:`ValueError`.
+Raising a negative number to a fractional power results in a :class:`complex`
+number. (Since Python 2.6. In earlier versions it raised a :exc:`ValueError`.)
.. _unary: