test_multiprocessing removes temporary files (GH-15421)

(cherry picked from commit d0b10a64)

Lib/test/test_multiprocessing.py

@@ -1809,6 +1809,7 @@ class _TestConnection(BaseTestCase):
         p = self.Process(target=self._writefd, args=(child_conn, b"foo"))
         p.daemon = True
         p.start()
+        self.addCleanup(support.unlink, support.TESTFN)
         with open(support.TESTFN, "wb") as f:
             fd = f.fileno()
             if msvcrt:
@@ -1834,6 +1835,7 @@ class _TestConnection(BaseTestCase):
         p = self.Process(target=self._writefd, args=(child_conn, b"bar", True))
         p.daemon = True
         p.start()
+        self.addCleanup(support.unlink, support.TESTFN)
         with open(support.TESTFN, "wb") as f:
             fd = f.fileno()
             for newfd in range(256, MAXFD):