fix raising exception.

src/wikiq/__init__.py

@@ -52,8 +52,8 @@ async def diff_async(differ, last_text, text):
         return differ.inline_json_diff(last_text, text)
     try:
         result = await asyncio.wait_for(_diff(), DIFF_TIMEOUT)
-    except asyncio.TimeoutError:
-        raise
+    except asyncio.TimeoutError as e:
+        raise e
     return result
 
 def calculate_persistence(tokens_added):