unfoldRepeats does not unfold abbreviated tremolos

[Denis Boirayon]

Hello,

I would like to use the abbreviated syntax for tremolos, but 
unfoldRepeats does not handle them as with the longer syntax:

% unfoldRepeats should unfold all tremolos (\repeat tremolo or ":" syntax).
% This version does not unfold b1:16
\version "2.19.83"
\relative c'' {
  \unfoldRepeats
  {
    b1:16
    \repeat tremolo 16 b16
  }
}

Thank you for your attention.
Denis