Issue 2801: fix bug in float.is_integer where ValueError was incorrectly

raised.

Misc/NEWS

@@ -12,6 +12,9 @@ What's new in Python 3.0b1?
 Core and Builtins
 -----------------
 
+- Issue 2801: fix bug in the float.is_integer method where a ValueError
+  was sometimes incorrectly raised.
+
 Extension Modules
 -----------------
 

Objects/floatobject.c

@@ -900,6 +900,7 @@ float_is_integer(PyObject *v)
 		return NULL;
 	if (!Py_IS_FINITE(x))
 		Py_RETURN_FALSE;
+	errno = 0;
 	PyFPE_START_PROTECT("is_integer", return NULL)
 	o = (floor(x) == x) ? Py_True : Py_False;
 	PyFPE_END_PROTECT(x)