It was some kind of workaround for DAG glitch in 2009
(commit hash 8c5c7ebb0) and according to the comment
was needed to make select outline show immediately.
After some tests it appears DAG behaves almost fine now
(just needed to make it so layer is flushed properly to
the set scene) and no reason to have rather confusing
call in the code.
ba15dd595f