FreeBSD doesn't follow C99 for modf(inf); so add explicit
special-value handling to math.modf code.
diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
index bb97a2c..0e91f8f 100644
--- a/Modules/mathmodule.c
+++ b/Modules/mathmodule.c
@@ -341,6 +341,15 @@
double y, x = PyFloat_AsDouble(arg);
if (x == -1.0 && PyErr_Occurred())
return NULL;
+ /* some platforms don't do the right thing for NaNs and
+ infinities, so we take care of special cases directly. */
+ if (!Py_IS_FINITE(x)) {
+ if (Py_IS_INFINITY(x))
+ return Py_BuildValue("(dd)", copysign(0., x), x);
+ else if (Py_IS_NAN(x))
+ return Py_BuildValue("(dd)", x, x);
+ }
+
errno = 0;
PyFPE_START_PROTECT("in math_modf", return 0);
x = modf(x, &y);