[3.10] bpo-47182: Fix crash by named unicode characters after interpreter reinitialization (GH-32212) (GH-32216)

Co-authored-by: Christian Heimes <[email protected]>

Author: tiran

Misc/NEWS.d/next/Core and Builtins/2022-03-31-15-37-02.bpo-47182.e_4SsC.rst

@@ -0,0 +1,2 @@
+Fix a crash when using a named unicode character like ``"\N{digit nine}"``
+after the main interpreter has been initialized a second time.

Objects/unicodeobject.c

@@ -16352,6 +16352,9 @@ _PyUnicode_Fini(PyInterpreterState *interp)
     if (_Py_IsMainInterpreter(interp)) {
         // _PyUnicode_ClearInterned() must be called before _PyUnicode_Fini()
         assert(interned == NULL);
+        // bpo-47182: force a unicodedata CAPI capsule re-import on
+        // subsequent initialization of main interpreter.
+        ucnhash_capi = NULL;
     }
 
     _PyUnicode_FiniEncodings(&state->fs_codec);