Regression: SchemaError during version upgrade

[nifgraup]

Steps
Run this minimal repro https://jsfiddle.net/av6gw2re/, same as the following:

const db = new Dexie("dbname");
db.version(1).stores({Y: "id"});
await db.open();
await db.close();

db.version(2).upgrade(trans => {
  console.log("Starting version 2 upgrade.")
  return trans.Y.count();
});
db.version(3).stores({
  Y: "id,X",
});
db.version(4).upgrade(trans => {
  console.log("Starting version 4 upgrade.")
  return trans.Y.where('X').equals('value').toArray();
});

try {
  await db.open();
} catch (e) {
  console.log(e);
} finally {
  await db.delete();
  console.log("All done.")
}

What happens

Starting version 2 upgrade.
Starting version 4 upgrade.
SchemaError: KeyPath X on object store Y is not indexed
All done.

Expected
No error as in Dexie 2:

Starting version 2 upgrade.
Starting version 4 upgrade.
All done.

[nifgraup]

Regression point

commit 718f78980a033c7eac2ed3140c0dd52b9f170a4f
Author: David Fahlander <david.fahlander@gmail.com>
Date:   Fri Jun 1 15:14:25 2018 +0200

    Issue713 (#714)
    
    Making it possible to rename a table and also change primary key.
    
    Resolves #713
    Resolves #105

[dfahlander]

Thanks @nifgraup for the concise repro. The issue was a memoization in Transaction - if a table had been queried in an earlier upgrade, the old schema was reused later on.