What happened to whiteout?

[Karol Majewski]

For some reason this gives horrible output:

=========BEGIN============

\version "2.19.22"

one = {
  \clef treble \key c \major \time 2/4 \tempo "Andantino"
  a'2 _\markup { \whiteout \pad-markup #0.5 { \dynamic p \italic "dolce" } } a'2
}

two = {
  \clef bass \key c \major \time 2/4
  c2 c2
}

\score {
  \new PianoStaff <<
    \new Staff = "one" \one
    \new Staff = "two" \two
  >>
}

=======END===========

In the second image (2.png) you can see even worse example of how whiteout 
works.

1.png
Description: PNG image

2.png
Description: PNG image