When the "copy" middleware tries to copy a segmented object which is
bigger than max_file_size, it immediatly returns "413 Request Entity Too
Large". But at that point, connections have already been established by
the proxy server to the object servers. These connections must be closed
before returning.
Closes-Bug: #1698207
Change-Id: I430c48c4a81e8392fa271160bcbc1817ef0a88f7