Add note about packages.

Author: ZeroIntensity

Doc/library/exceptions.rst

@@ -566,12 +566,13 @@ The following exceptions are the exceptions that are usually raised.
    this could be raised by incorrectly using Python's C API, such as returning
    a ``NULL`` value without an exception set.
 
-   If you're confident that this exception wasn't your fault, you should
-   report this to the author or maintainer of your Python interpreter.
-   Be sure to report the version of the Python interpreter (``sys.version``; it is
-   also printed at the start of an interactive Python session), the exact error
-   message (the exception's associated value) and if possible the source of the
-   program that triggered the error.
+   If you're confident that this exception wasn't your fault, or the fault of
+   a package you're using, you should report this to the author or maintainer
+   of your Python interpreter. Be sure to report the version of the Python
+   interpreter (``sys.version``; it is also printed at the start of an
+   interactive Python session), the exact error message (the exception's
+   associated value) and if possible the source of the program that triggered
+   the error.
 
 
 .. exception:: SystemExit