proto: Remove error message which hides earlier error.

When chunked encoding fails, the following error is added to
the handle:

  [filename]: error in chunked encoding

However all paths returning -1 from receive_file_data already set a
more specific error, which this error hides.

src/proto.c

@@ -781,7 +781,6 @@ guestfs___recv_file (guestfs_h *g, const char *filename)
   }
 
   if (r == -1) {
-    error (g, _("%s: error in chunked encoding"), filename);
     close (fd);
     return -1;
   }