@krypterro
The solution to the above problem is
data = PandasData_Extend(dataname=data_df)
I was not extending the class properly.

To those that may come across this thread, I cannot explain why the issue is occurring, but if you pass a name to the default data when utilizing 'adddata', the legend will look normal again. Fixed

#Don't use this: cerebro.adddata(data) #Use a name with the data: cerebro.adddata(data, name='OHLCV_jt')

The name comes across in the heading / legend of the master Bokeh plot as so:
snapshot1.PNG

Thanks. Found how to suppress it indeed. Reference for future generations: https://www.jetbrains.com/help/pycharm/suppressing-inspections.html

In this case it'll look like this:

# noinspection PyArgumentList data = PData(dataname=df)

Thank you very much @backtrader. I didn't notice that thread. The solution works like a charm.

@btr said in Programmatically extending a datafeed:

I needed a break and coffee. It was silly

Hilarious! Hope you had a nice break!

A sample of the returned value would be needed. Else use the native Quandl support available in the last release. It has only been tested with the WIKI dataset though.

See Docs - Data Feeds Reference