bpo-33671 fix orphaned comment in shutil.copyfileobj (GH-27516)

Author: asottile

Lib/shutil.py

@@ -188,9 +188,9 @@ def _copyfileobj_readinto(fsrc, fdst, length=COPY_BUFSIZE):
 
 def copyfileobj(fsrc, fdst, length=0):
     """copy data from file-like object fsrc to file-like object fdst"""
-    # Localize variable access to minimize overhead.
     if not length:
         length = COPY_BUFSIZE
+    # Localize variable access to minimize overhead.
     fsrc_read = fsrc.read
     fdst_write = fdst.write
     while True: