I am looking at
 pkg/35152: graphics/png: distinfo is wrong

I tested and it attempted to download over and over again.

Each time saying:

  fetch: Unable to verify fetched file libpng-1.2.14.tar.bz2

This is a different behaviour than we used to have.

It used to fail the first time if checksum didn't match and would try next 
mirror.

I don't think I like this new behaviour. I am not sure when this 
changed.... maybe in July.

I don't see anyway to turn this off. Any hints?