bpo-24596: Decref module in PyRun_SimpleFileExFlags() on SystemExit (GH-7918) (GH-8070)

PyErr_Print() will not return when the exception is a SystemExit, so
decref the __main__ module object in that case.
(cherry picked from commit d8cba5d16f1333fd625726fc72e66afbd45b8d00)

Co-authored-by: Zackery Spytz <zspytz@gmail.com>
diff --git a/Lib/test/test_gc.py b/Lib/test/test_gc.py
index 904fc7d..8d806db 100644
--- a/Lib/test/test_gc.py
+++ b/Lib/test/test_gc.py
@@ -1,7 +1,7 @@
 import unittest
 from test.support import (verbose, refcount_test, run_unittest,
                           strip_python_stderr, cpython_only, start_threads,
-                          temp_dir, requires_type_collecting)
+                          temp_dir, requires_type_collecting, TESTFN, unlink)
 from test.support.script_helper import assert_python_ok, make_script
 
 import sys
@@ -708,6 +708,21 @@
             rc, out, err = assert_python_ok('-c', code)
             self.assertEqual(out.strip(), b'__del__ called')
 
+    @requires_type_collecting
+    def test_global_del_SystemExit(self):
+        code = """if 1:
+            class ClassWithDel:
+                def __del__(self):
+                    print('__del__ called')
+            a = ClassWithDel()
+            a.link = a
+            raise SystemExit(0)"""
+        self.addCleanup(unlink, TESTFN)
+        with open(TESTFN, 'w') as script:
+            script.write(code)
+        rc, out, err = assert_python_ok(TESTFN)
+        self.assertEqual(out.strip(), b'__del__ called')
+
     def test_get_stats(self):
         stats = gc.get_stats()
         self.assertEqual(len(stats), 3)