gh-108834: regrtest --fail-rerun exits with code 5 (#108896)

When the --fail-rerun option is used and a test fails and then pass,
regrtest now uses exit code 5 ("rerun) instead of 2 ("bad test").

(cherry picked from commit 1170d5a)

Lib/test/libregrtest/main.py

@@ -29,9 +29,10 @@
 EXIT_TIMEOUT = 120.0
 
 EXITCODE_BAD_TEST = 2
-EXITCODE_INTERRUPTED = 130
 EXITCODE_ENV_CHANGED = 3
 EXITCODE_NO_TESTS_RAN = 4
+EXITCODE_RERUN_FAIL = 5
+EXITCODE_INTERRUPTED = 130
 
 
 class Regrtest:
@@ -840,7 +841,7 @@ def get_exitcode(self):
         elif self.no_tests_run():
             exitcode = EXITCODE_NO_TESTS_RAN
         elif self.rerun and self.ns.fail_rerun:
-            exitcode = EXITCODE_BAD_TEST
+            exitcode = EXITCODE_RERUN_FAIL
         return exitcode
 
     def action_run_tests(self):

Lib/test/test_regrtest.py

@@ -34,6 +34,7 @@
 EXITCODE_BAD_TEST = 2
 EXITCODE_ENV_CHANGED = 3
 EXITCODE_NO_TESTS_RAN = 4
+EXITCODE_RERUN_FAIL = 5
 EXITCODE_INTERRUPTED = 130
 
 TEST_INTERRUPTED = textwrap.dedent("""
@@ -1261,10 +1262,10 @@ def test_fail_once(self):
                                   stats=TestStats(3, 1))
         os_helper.unlink(marker_filename)
 
-        # with --fail-rerun, exit code EXITCODE_BAD_TEST
+        # with --fail-rerun, exit code EXITCODE_RERUN_FAIL
         # on "FAILURE then SUCCESS" state.
         output = self.run_tests("--rerun", "--fail-rerun", testname,
-                                exitcode=EXITCODE_BAD_TEST)
+                                exitcode=EXITCODE_RERUN_FAIL)
         self.check_executed_tests(output, [testname],
                                   rerun=Rerun(testname,
                                               match="test_fail_once",