Note change in behavior from 1.5.2. The new argument to NameError is

an error message and not just the missing name.

Closes SF Bug 599869.

Doc/lib/libexcs.tex

@@ -206,8 +206,8 @@ Raised when an \keyword{assert} statement fails.
 
 \begin{excdesc}{NameError}
   Raised when a local or global name is not found.  This applies only
-  to unqualified names.  The associated value is the name that could
-  not be found.
+  to unqualified names.  The associated value is an error message that
+  includes the name that could not be found.
 \end{excdesc}
 
 \begin{excdesc}{NotImplementedError}