threading: update for py39 (#4087)

stdlib/2and3/_dummy_threading.pyi

@@ -75,7 +75,8 @@ class Thread:
         @property
         def native_id(self) -> Optional[int]: ...  # only available on some platforms
     def is_alive(self) -> bool: ...
-    def isAlive(self) -> bool: ...
+    if sys.version_info < (3, 9):
+        def isAlive(self) -> bool: ...
     def isDaemon(self) -> bool: ...
     def setDaemon(self, daemonic: bool) -> None: ...
 
@@ -143,7 +144,10 @@ class Semaphore:
         def acquire(self, blocking: bool = ..., timeout: float = ...) -> bool: ...
     else:
         def acquire(self, blocking: bool = ...) -> bool: ...
-    def release(self) -> None: ...
+    if sys.version_info >= (3, 9):
+        def release(self, n: int = ...) -> None: ...
+    else:
+        def release(self) -> None: ...
 
 class BoundedSemaphore(Semaphore): ...
 

stdlib/2and3/threading.pyi

@@ -75,7 +75,8 @@ class Thread:
         @property
         def native_id(self) -> Optional[int]: ...  # only available on some platforms
     def is_alive(self) -> bool: ...
-    def isAlive(self) -> bool: ...
+    if sys.version_info < (3, 9):
+        def isAlive(self) -> bool: ...
     def isDaemon(self) -> bool: ...
     def setDaemon(self, daemonic: bool) -> None: ...
 
@@ -143,7 +144,10 @@ class Semaphore:
         def acquire(self, blocking: bool = ..., timeout: float = ...) -> bool: ...
     else:
         def acquire(self, blocking: bool = ...) -> bool: ...
-    def release(self) -> None: ...
+    if sys.version_info >= (3, 9):
+        def release(self, n: int = ...) -> None: ...
+    else:
+        def release(self) -> None: ...
 
 class BoundedSemaphore(Semaphore): ...