MIRI UB in rowan `Arc::drop`

[dnbln]

error: Undefined Behavior: write access through <3644568> at alloc1395441[0x0] is forbidden
   --> /Users/dinu/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/rowan-0.16.1/src/arc.rs:162:12
    |
162 |         if self.inner().count.fetch_sub(1, Release) != 1 {
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ write access through <3644568> at alloc1395441[0x0] is forbidden
    |
    = help: this indicates a potential bug in the program: it performed an invalid operation, but the Tree Borrows rules it violated are still experimental
    = help: the accessed tag <3644568> has state Frozen which forbids this child write access
help: the accessed tag <3644568> was created here, in the initial state Frozen

[bjorn3]

Does it work with MIRIFLAGS="-Zmiri-tree-borrows"?

[dnbln]

That was from when I ran it with -Zmiri-tree-borrows. It also fails with Stacked Borrows, although in a different place