_extract_member, raised an exception in case of more than one process, This happens because "not os.path.exists(upperdirs" return True in case of multiprocess


CODE:
.............
        if upperdirs and not os.path.exists(upperdirs):
            # Create directories that are not part of the archive with
            # default permissions.
            os.makedirs(upperdirs)
................


I solved the problem by creating the root path before like:
        try:
            os.makedirs(path)
        except OSError as e:
            if e.errno != os.errno.EEXIST:
                raise
            pass

there is an option to add :  
if e.errno != os.errno.EEXIST: in your code?