MusicXML export cannot handle tempo as "= about [nn]"

MuseScore 2.0.2 revision f51dc11
Windows 7

Exporting as XML works fine when the tempo does not use the word "about".
For example "Allegro e leggiero (metNoteQuarterUp = 120)".
CORRECT TEMPO DIRECTION:

        <direction-type>
          <words font-weight="bold" font-size="12">Allegro e leggiero </words>
          </direction-type>
        <direction-type>
          <metronome parentheses="yes">
            <beat-unit>quarter</beat-unit>
            <per-minute>120</per-minute>
            </metronome>
          </direction-type>
        <staff>1</staff>
        <sound tempo="120"/>
        </direction>

But if the word "about" is used before the tempo BPM, the XML export loses its way a bit.
For example "Allegro e leggiero (metNoteQuarterUp = about 120)".
BROKEN TEMPO DIRECTION:

        <direction-type>
          <words font-weight="bold" font-size="12">Allegro e leggiero (</words>
          </direction-type>
        <direction-type>
          <metronome parentheses="no">
            <beat-unit>quarter</beat-unit>
            <per-minute></per-minute>
            </metronome>
          </direction-type>
        <direction-type>
          <words font-weight="bold" font-size="12">about 120)</words>
          </direction-type>
        <staff>1</staff>
        <sound tempo="120"/>
        </direction>

This export leaves empty the "per-minute" property, which is not valid MusicXML. It also declares "metronome parentheses" as "no", when actually it should be "yes".

Example MSCZ files are attached.