shutil: copyfileobj(): Support file objects without readinto() method.

shutil/shutil.py

@@ -9,13 +9,20 @@ def rmtree(top):
         os.rmdir(path)
 
 def copyfileobj(src, dest, length=512):
-    buf = bytearray(length)
+    if hasattr(src, "readinto"):
-    while True:
+        buf = bytearray(length)
-        sz = src.readinto(buf)
+        while True:
-        if not sz:
+            sz = src.readinto(buf)
-            break
+            if not sz:
-        if sz == length:
+                break
+            if sz == length:
+                dest.write(buf)
+            else:
+                b = memoryview(buf)[:sz]
+                dest.write(b)
+    else:
+        while True:
+            buf = src.read(length)
+            if not buf:
+                break
             dest.write(buf)
-        else:
-            b = memoryview(buf)[:sz]
-            dest.write(b)