[3.9] bpo-46263: FreeBSD 14.0 jemalloc workaround for junk bytes of freed memory (GH-30434) (GH-30437)

Co-authored-by: Christian Heimes <christian@python.org>

Author: miss-islington

Lib/test/test_capi.py

@@ -763,8 +763,13 @@ class PyMemDebugTests(unittest.TestCase):
 
     def check(self, code):
         with support.SuppressCrashReport():
-            out = assert_python_failure('-c', code,
-                                        PYTHONMALLOC=self.PYTHONMALLOC)
+            out = assert_python_failure(
+                '-c', code,
+                PYTHONMALLOC=self.PYTHONMALLOC,
+                # FreeBSD: instruct jemalloc to not fill freed() memory
+                # with junk byte 0x5a, see JEMALLOC(3)
+                MALLOC_CONF="junk:false",
+            )
         stderr = out.err
         return stderr.decode('ascii', 'replace')
 

Misc/NEWS.d/next/Tests/2022-01-06-15-45-34.bpo-46263.bJXek6.rst

@@ -0,0 +1,2 @@
+Fix test_capi on FreeBSD 14-dev: instruct jemalloc to not fill freed memory
+with junk byte.