Fix inappropriate "break in finally"

CHANGES/10434.bugfix.rst

@@ -0,0 +1,2 @@
+Avoid break statement inside the finally block in :py:class:`~aiohttp.web.RequestHandler`
+-- by :user:`Cycloctane`.

aiohttp/web_protocol.py

@@ -633,26 +633,28 @@ async def start(self) -> None:
 
             except asyncio.CancelledError:
                 self.log_debug("Ignored premature client disconnection")
+                self.force_close()
                 raise
             except Exception as exc:
                 self.log_exception("Unhandled exception", exc_info=exc)
                 self.force_close()
+            except BaseException:
+                self.force_close()
+                raise
             finally:
                 if self.transport is None and resp is not None:
                     self.log_debug("Ignored premature client disconnection.")
-                elif not self._force_close:
-                    if self._keepalive and not self._close:
-                        # start keep-alive timer
-                        if keepalive_timeout is not None:
-                            now = loop.time()
-                            close_time = now + keepalive_timeout
-                            self._next_keepalive_close_time = close_time
-                            if self._keepalive_handle is None:
-                                self._keepalive_handle = loop.call_at(
-                                    close_time, self._process_keepalive
-                                )
-                    else:
-                        break
+
+            if self._keepalive and not self._close and not self._force_close:
+                # start keep-alive timer
+                close_time = loop.time() + keepalive_timeout
+                self._next_keepalive_close_time = close_time
+                if self._keepalive_handle is None:
+                    self._keepalive_handle = loop.call_at(
+                        close_time, self._process_keepalive
+                    )
+            else:
+                break
 
         # remove handler, close transport if no handlers left
         if not self._force_close:

tests/test_web_server.py

@@ -248,6 +248,24 @@ async def handler(request: web.BaseRequest) -> NoReturn:
     logger.debug.assert_called_with("Ignored premature client disconnection")
 
 
+async def test_raw_server_does_not_swallow_base_exceptions(
+    aiohttp_raw_server: AiohttpRawServer, aiohttp_client: AiohttpClient
+) -> None:
+    class UnexpectedException(BaseException):
+        """Dummy base exception."""
+
+    async def handler(request: web.BaseRequest) -> NoReturn:
+        raise UnexpectedException()
+
+    loop = asyncio.get_event_loop()
+    loop.set_debug(True)
+    server = await aiohttp_raw_server(handler)
+    cli = await aiohttp_client(server)
+
+    with pytest.raises(client.ServerDisconnectedError):
+        await cli.get("/path/to", timeout=client.ClientTimeout(10))
+
+
 async def test_raw_server_cancelled_in_write_eof(
     aiohttp_raw_server: AiohttpRawServer, aiohttp_client: AiohttpClient
 ) -> None: