Update _posixsubprocess module for 3.14 (#14127)

Author: sobolevn

stdlib/@tests/stubtest_allowlists/darwin-py314.txt

@@ -2,7 +2,6 @@
 # TODO: New errors in Python 3.14 that need to be fixed or moved below
 # ====================================================================
 
-_posixsubprocess.fork_exec
 asyncio.tools
 asyncio.unix_events.__all__
 asyncio.unix_events.DefaultEventLoopPolicy

stdlib/@tests/stubtest_allowlists/linux-py314.txt

@@ -2,7 +2,6 @@
 # TODO: New errors in Python 3.14 that need to be fixed or moved below
 # ====================================================================
 
-_posixsubprocess.fork_exec
 asyncio.tools
 asyncio.unix_events.__all__
 asyncio.unix_events.DefaultEventLoopPolicy

stdlib/_posixsubprocess.pyi

@@ -4,29 +4,56 @@ from collections.abc import Callable, Sequence
 from typing import SupportsIndex
 
 if sys.platform != "win32":
-    def fork_exec(
-        args: Sequence[StrOrBytesPath] | None,
-        executable_list: Sequence[bytes],
-        close_fds: bool,
-        pass_fds: tuple[int, ...],
-        cwd: str,
-        env: Sequence[bytes] | None,
-        p2cread: int,
-        p2cwrite: int,
-        c2pread: int,
-        c2pwrite: int,
-        errread: int,
-        errwrite: int,
-        errpipe_read: int,
-        errpipe_write: int,
-        restore_signals: int,
-        call_setsid: int,
-        pgid_to_set: int,
-        gid: SupportsIndex | None,
-        extra_groups: list[int] | None,
-        uid: SupportsIndex | None,
-        child_umask: int,
-        preexec_fn: Callable[[], None],
-        allow_vfork: bool,
-        /,
-    ) -> int: ...
+    if sys.version_info >= (3, 14):
+        def fork_exec(
+            args: Sequence[StrOrBytesPath] | None,
+            executable_list: Sequence[bytes],
+            close_fds: bool,
+            pass_fds: tuple[int, ...],
+            cwd: str,
+            env: Sequence[bytes] | None,
+            p2cread: int,
+            p2cwrite: int,
+            c2pread: int,
+            c2pwrite: int,
+            errread: int,
+            errwrite: int,
+            errpipe_read: int,
+            errpipe_write: int,
+            restore_signals: int,
+            call_setsid: int,
+            pgid_to_set: int,
+            gid: SupportsIndex | None,
+            extra_groups: list[int] | None,
+            uid: SupportsIndex | None,
+            child_umask: int,
+            preexec_fn: Callable[[], None],
+            /,
+        ) -> int: ...
+    else:
+        def fork_exec(
+            args: Sequence[StrOrBytesPath] | None,
+            executable_list: Sequence[bytes],
+            close_fds: bool,
+            pass_fds: tuple[int, ...],
+            cwd: str,
+            env: Sequence[bytes] | None,
+            p2cread: int,
+            p2cwrite: int,
+            c2pread: int,
+            c2pwrite: int,
+            errread: int,
+            errwrite: int,
+            errpipe_read: int,
+            errpipe_write: int,
+            restore_signals: bool,
+            call_setsid: bool,
+            pgid_to_set: int,
+            gid: SupportsIndex | None,
+            extra_groups: list[int] | None,
+            uid: SupportsIndex | None,
+            child_umask: int,
+            preexec_fn: Callable[[], None],
+            allow_vfork: bool,
+            /,
+        ) -> int: ...