Fix logging.Logger.isEnabledFor() to return bool instead of None.

Author: Peter Amstutz

stdlib/2and3/logging/__init__.pyi

@@ -26,7 +26,7 @@ class Logger:
     handlers = ... # type: List[Handler]
     disabled = ... # type: int
     def setLevel(self, lvl: Union[int, str]) -> None: ...
-    def isEnabledFor(self, lvl: int) -> None: ...
+    def isEnabledFor(self, lvl: int) -> Union[int, bool]: ...
     def getEffectiveLevel(self) -> int: ...
     def getChild(self, suffix: str) -> 'Logger': ...
     if sys.version_info > (3,):
@@ -240,7 +240,7 @@ class LoggerAdapter:
         def log(self,
                 lvl: int, msg: Text, *args: Any, exc_info: _ExcInfoType = ...,
                 extra: Dict[str, Any] = ..., **kwargs: Any) -> None: ...
-    def isEnabledFor(self, lvl: int) -> None: ...
+    def isEnabledFor(self, lvl: int) -> Union[int, bool]: ...
     if sys.version_info >= (3,):
         def getEffectiveLevel(self) -> int: ...
         def setLevel(self, lvl: Union[int, str]) -> None: ...