Add asserts to check for 'impossible' NULL values, with comments.
In one place where I'm not 1000% sure about the non-NULL, raise
a RuntimeError for safety.

This should fix the klocwork issues that Neal sent me.  If so,
it should be applied to the release25-maint branch also.

Also make sure that every exception class has __module__ set to
'exceptions'.
 (backport)

imports (if not in package and if beyond toplevel package).
 (backport from rev. 51765)

of os.urandom().
 (backport from rev. 51762)

making subprocess not close standard file descriptors.

to use "in".
 (backport from rev. 51740)

Backport 51669: Make sure memory is properly cleaned up in file_init (even though this should not be able to happen since we already parsed the args)

generator expressions (x for x, in ... ) works again.

Sigh, I only fixed for loops the first time, not list comps and genexprs too.
I couldn't find any more unpacking cases where there is a similar bug lurking.

Partially from SF patch #1551339, but also taken from head.

checking to live happily with recent gcc optimizations that
assume signed integer arithmetic never overflows.

  Doc fix: hashlib objects don't always return a digest of 16 bytes.

 (backport from rev. 51677)

- various minor cleanups for improved consistency

  a unicode string in a build with wide unicode (UCS-4) support.

I will forward port to 2.6.  Can someone backport to 2.4?

Handle a few more error conditions.

Klocwork 301 and 302.  Will backport.

Fix bug #1543303, tarfile adds padding that breaks gunzip.
Patch # 1543897.  (remove the padding)

 (backport from rev. 51416)

object so we don't leak op.  (Fixes an earlier patch to this code)

Klockwork #350