restore start==0 fast path to avoid needless copy

deadlovelll · deadlovelll · commit f1b97ca9037a · 2026-07-25T11:38:32.000+03:00
diff --git a/Lib/asyncio/protocols.py b/Lib/asyncio/protocols.py
@@ -207,7 +207,7 @@ def _feed_data_to_buffered_proto(proto, data):
             raise RuntimeError('get_buffer() returned an empty buffer')
 
         if buf_len >= data_len:
-            buf[:data_len] = data[start:]
+            buf[:data_len] = data[start:] if start else data
             proto.buffer_updated(data_len)
             return
         else:
