Strange interaction between chord names, \markLengthOn and \fermata

[Davide Liessi]

Hi all.
In the following example the mark "some long texts" is placed between
the chord names, thus creating extra space around the bar line;
removing either \fermata, \markLengthOn or accidentals in chord names,
the mark is placed above the chord names and the extra space
disappears.
Can someone explain why this happens?
Best wishes.
Davide

\version "2.19.35"
\score {
  <<
    \new ChordNames {
      \chordmode {
        cis1
        cis1
      }
    }
    \new Staff {
      \markLengthOn
      c'1\fermata
      \mark "some long text"
      c'1
    }
  >>
}