Depending on the circumstance, "tail wagging" can mean:
1. "Oh please, do me, do me" (from a receptive female) often accompanied by an everted cloaca pressed to the substrate, spreading fluids about.
2. "Oh noooo, I'm afraid someone's trying to do me" (particularly with young, naive females), usually with the female seeming to continually flee from a male's attention.
3. "I'm feeling really intimidated by this situation right now, so if you don't back off and get the heck outta my grill, I'm going to have to change my alert level to DefCon 4 and launch my teeth at you." Kinda cute with a tiny snake; not so much with any of the fully-grown giant snakes or irascible blood pythons.
And maybe what Kyra said regarding caudal luring in species not known for that trait. I might have seen something like that with ball pythons long ago when I fed live rodents, but can't recall seeing such any time recently.
Edit: Funny, I ended up in this thread by searching on "Angolan" to see who else might be keeping that species and didn't notice that it was a few weeks old, and then started reading and forgot about the Angolan search and replied. Oops.