update='append' does not work anymore

[chenyuntc]

simple code to reproduce

import numpy as np
import visdom
vis = visdom.Visdom()
vis.line(np.arange(3),np.arange(3),win='test')
vis.line(np.arange(3),np.arange(3)+3,win='test',update='append')

It used to work, but I update visdom and it won't work any more.
I guess the problem comes from here

If I change it to :

        name = args.get('name')
        append = args.get('append')
        if name is None and append is None:
            return p  # we only updated the opts or layout

It works again. But I don't know whether it was the right way.

Since I use it a lot in my project and many other, I really hope it could be fix eariler.

Thanks for your great job to create such a lightweight and powerful visulization tool!

[JackUrb]

Ack sorry about this bug, going to push a fix right now. Pretty close to what you had, but I'm going to case it on the existence of new_data rather than append, which will fix appends and updates