See https://github.com/ppy/osu/pull/30215#issuecomment-2407775408 for
context.
Turns out the test failures were more correct than I'd thought. The
long-and-short of it is that both in "pure random" mode and in
"permutation" mode, when running out of track history to fall
back on, it was possible for the random algorithm to pick the same song
twice in a row - which is probably not desired, and which this explicit
exclude should make impossible.
Closes https://github.com/ppy/osu/issues/30163.
If I'm to be blunt, the decoupled stuff in song select makes my head
spin. I spent a solid 20 minutes thinking how I was going to fix this
one but then finally realised that generally most of the cause there
was the fact that `AdvancedStats` was seeing the new rulesets *before*
the "ensure global selected mods are valid for current ruleset" logic,
and so decided to just _delay_ that until the decoupled transfer
thingamajig happens.
I was honestly considering combining `BeatmapInfo`, `Ruleset`, and
`Mods` into one property on `AdvancedStats`. I figured I'd rather not
push my luck and try the baseline version first, but I honestly think
that direction is going to be required at some point to properly corral
all of the decoupled madness taking place in song select.
Whomst've thought this was an ok thing to do? How did this pass review?
Let's leave these as rhetorical questions right now. Huge chances are
I'd implicate myself with at least one of them.
I'm not sure why this was "fine" for as long as it apparently was,
but what `MusicController` was doing was completely incorrect and
playing with fire (accessing raw managed realm objects), which went
wrong somewhere around - admittedly -
https://github.com/ppy/osu/pull/29917, likely because that one started
*storing* these raw managed realm objects to fields, and you know what
will happen to those after you do a migration and recycle realms.
To attempt to circumvent this, (ab)use `DetachedBeatmapStore` instead.
Which does necessitate moving it to `OsuGameBase`, but it's the simplest
way out I can see. I guess the alternative would be to faff around with
`Live<T>` but it's ugly and I'm attempting to fix this relatively quick
right now.
