Allocating with arena and also its child allocator (HeapAllocator at least) causes crash

[lxn]

This is on Windows 10 using zig-windows-x86_64-0.6.0+12a7dedb1.zip.

No problems before recent Allocator changes.

const std = @import("std");

pub fn main() anyerror!void {
    var heap_allocator = std.heap.HeapAllocator.init();
    defer heap_allocator.deinit();
    const allocator = &heap_allocator.allocator;

    var arena = std.heap.ArenaAllocator.init(allocator);
    defer arena.deinit();
    const arena_allocator = &arena.allocator;

    // Allocating an u8 instead of u16 for foo would avoid the crash on allocating bar.
    const foo = try arena_allocator.create(u16);

    // Allocating bar before foo would crash on "defer arena.deinit();" instead.
    const bar = try allocator.create(u8);
    defer allocator.destroy(bar);
}