gh-118201: Accomodate flaky behavior of `os.sysconf` on iOS (GH-118453)

Lib/test/support/os_helper.py

@@ -632,7 +632,8 @@ def fd_count():
     if hasattr(os, 'sysconf'):
         try:
             MAXFD = os.sysconf("SC_OPEN_MAX")
-        except OSError:
+        except (OSError, ValueError):
+            # gh-118201: ValueError is raised intermittently on iOS
             pass
 
     old_modes = None

Lib/test/test_os.py

@@ -2365,6 +2365,7 @@ class TestInvalidFD(unittest.TestCase):
         support.is_emscripten or support.is_wasi,
         "musl libc issue on Emscripten/WASI, bpo-46390"
     )
+    @unittest.skipIf(support.is_apple_mobile, "gh-118201: Test is flaky on iOS")
     def test_fpathconf(self):
         self.check(os.pathconf, "PC_NAME_MAX")
         self.check(os.fpathconf, "PC_NAME_MAX")