R1:df661eca355b

Always run "behavior-populate" before "behavior-show-more"

Summary:
Ref T2009. This clears the stage for D11977.

Specifically, D11977 moves "show context" logic into ChangesetViewManager, but those objects won't exist if we don't run "behavior-populate" first.

Generally, this increases consistency across changeset views -- which is still very low overall, but getting slightly better.

Both of these should probably move up more and use ChangesetListView, but we don't need to do that quite yet.

Test Plan…