When two object are changed by two users rebase does not work as intented.

[khanaffan]

It seems when placement is changed conflict hander is never called and incoming change replaces local change.

In this case locally deleted element pop back up during rebase.

To Reproduce
Steps to reproduce the behavior:

1. With no locks. This is not normal and related to branching.
2. Change location of graphical element on briefcase 1 and push
3. Delete the element on briefcase 2 and pull merge.
4. The deleted element will pop back up and it's also removed from the txn after rebasing.
5. It observes this only happen when placement is changed otherwise it does get deleted.

Here is a test and branch is set that have following test.

 it.only("delete instance (data conflict) ", async () => {
    const b1 = await ctx.openB1(true /* = noLock */);
    const b2 = await ctx.openB2(true /* = noLock */);

    const e1 = await insertPhysicalObject(b1);
    b1.saveChanges();
    await b1.pushChanges({ description: `inserted physical object [id=${e1}]` });
    await b2.pullChanges();

    const eb1 = b1.elements.getElementProps<PhysicalElementProps>(e1);
    eb1.userLabel = "test1";
    eb1.placement = { origin: { x: 1, y: 1, z: 1 }, angles: { yaw: 1, pitch: 1, roll: 1 } };
    b1.elements.updateElement(eb1);
    b1.saveChanges();
    await b1.pushChanges({ description: `update physical object [id=${e1}]` });

    b2.elements.deleteElement(e1);;
    b2.saveChanges();
    await b2.pullChanges();

    const eb2 = b2.elements.tryGetElementProps<PhysicalElementProps>(e1); // should throw
    assert.isUndefined(eb2);

    b1.close();
    b2.close();
  });

Expected behavior
The element should stay deleted.

reported by : @wgoehrig