Issue #18426: Fix NULL pointer dereference in C extension import when

PyModule_GetDef() returns an error.

diff --cc Misc/NEWS
index ed579ef1f7a1d82e4bd6696f035412174afbc446,4d55853af7f961509aad6e4e953938f7480b2cb8..96e51e38fbfcca32dfd129f14d10fbe5a16d660b
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -10,13 -12,9 +10,16 @@@ What's New in Python 3.4.0 Alpha 1
  Core and Builtins
  -----------------
  
+ - Issue #18426: Fix NULL pointer dereference in C extension import when
+   PyModule_GetDef() returns an error.
+ 
 +- Issue #17206: On Windows, increase the stack size from 2 MB to 4.2 MB to fix
 +  a stack overflow in the marshal module (fix a crash in test_marshal).
 +  Patch written by Jeremy Kloth.
 +
 +- Issue #3329: Implement the PEP 445: Add new APIs to customize Python memory
 +  allocators.
 +
  - Issue #18328: Reorder ops in PyThreadState_Delete*() functions. Now the
    tstate is first removed from TLS and then deallocated.