When I try to update @system after --sync-ing, I get a conflict on readline.

Bash wants readline 8.0 but the profile specifies readline 7.0 and lots of other packages are linked against 7.0.  Just rebuilding those packages probably won't help, because they don't know about readline 8.0.

Would the right thing, the easiest thing, be to define my own profile 17.1.1 or something, where I specify readline 8.0 in the profile?