I’m using Firefox 48.0a1 Nightly without AdBlock installed, but I still get this “please disable …” message. Annoying - the bot needs to learn about Nightly, I think …
Do you, perchance, have any other blockers or something running?
For example, in addition to AdBlock I also use GlimmerBlocker (OS X), Privacy Badger, umatrix, which I have all disabled for OGS.