It has been a couple years since I got a “update bundler” prompt. I figured “latest is best” and upgraded bundler.
Unfortunely, at that time, some of what Discourse needed to be in bundler was not in the upgraded bundler. I had to start over and ignore that with a no
But “linux” last got a commit a month ago, so I would guess it should be OK to upgrade bundler. Worse case, you will need to start over. Else wait for techAPJ to reply.