Document that PyString_FromString() cannot take NULL as a parameter.
This closes SF bug #489872.
diff --git a/Doc/api/concrete.tex b/Doc/api/concrete.tex
index 6c6e6f5..a476e37 100644
--- a/Doc/api/concrete.tex
+++ b/Doc/api/concrete.tex
@@ -463,7 +463,8 @@
\begin{cfuncdesc}{PyObject*}{PyString_FromString}{const char *v}
Returns a new string object with the value \var{v} on success, and
- \NULL{} on failure.
+ \NULL{} on failure. The parameter \var{v} must not be \NULL; it
+ will not be checked.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyString_FromStringAndSize}{const char *v,