I assumed we were talking about them "relicensing" the content from the all-rights-reserved-whatever to cc-by-sa. In hindsight that was poor wording on my part

I assumed we were talking about them "relicensing" the content from the all-rights-reserved-whatever to cc-by-sa. In hindsight that was poor wording on my part because it wouldn't actually be "relicensing" since the contributor is contributing it under cc-by-sa to begin with. So no relicensing is necessary. In my first comment I said cc-by-sa 4.0 because I had just gone to the site footer to see what license they were using. I knew it was some form of creative commons, but I didn't know which one. I didn't know until just now that they are changing (or trying to change) the license on all existing content from cc-by-sa 3.0 to cc-by-sa 4.0. That I doubt they can do and I very much disagree with the move even if they can. Interestingly, they also appear to have unilaterally changed the license on all content from cc-by-sa 2.5 to cc-by-sa 3.0 in 2011. The comment on Jeff Atwood's answer at https://meta.stackexchange.com/a/95033 https://meta.stackexchange.com/a/95033 is fun.