Working set is broken after Save As (or save untitled) outside project

[peterflynn]

1. Open several files in the working set
2. Select the first one
3. Save As, and choose a location outside the project root

Result: Newly saved filename appears at bottom of working set, and original filename is still listed at top of list. If original file was untitled, clicking it throws assertions.

Expected: Item at top of list is replaced with new filename. (Working set length is unchanged).

[bchintx]

@peterflynn Thanks for writing this up. @iwehrman found the same thing earlier today too.

PR #4479 should fix this issue.

[peterflynn]

@bchintx I think it doesn't fix it fully -- see my notes over in the PR.

[peterflynn]

We should add a unit test for this case before closing the bug.

[bchintx]

@peterflynn I've updated PR #4479 to take care of the additional issues mentioned in that same PR discussion.

As requested, I've also added unit test "Integration/DocumentCommandHandlers" for this case.

Re: the other issues recently referenced:
I can't reproduce Issue #4468 at all on either my Windows or Mac builds. PR #4487 looks already approved/merged. Finally, I haven't investigated Issue #4494 yet.

[peterflynn]

Closing -- fix has been merged