I'm an idiot. I linked an old .blend I used for another report. Sorry, same file name different folders!
Another thing I forgot to point out earlier: the negative values are found not in black pizels but in supersaturated ones.
Here is the right one with the packed image.

Thank you for the file.
Should I report an error in the documentation? See the seed description here
I thought it was weird to see the seed value of zero implemented as a sentinel...
Where should I make a feature request to have a checkbox for a non random halo style?

I included two renders showing how rings and lines appear random at seed 0

Thank you for your swift response!

Sorry, I thought the manual covered all the features the official release only, not in dev builds as well. Sorry for the false alarm!

Tried in 2.74 000dfc0
Same thing

Flipping the reference with F works though.