[metapost] Bug with "odd" primitive?

[Toby Thurston]

The "odd" primitive appears to return "false" for all negative numbers.  This behaviour is significantly different from Metafont. 
Can we get it corrected?  Or at least documented?  Thanks Toby

Test program:

    show(odd -3); end

result with Metafont:

    This is METAFONT, Version 2.7182818 (TeX Live 2014) (preloaded base=mf)
    (test.mf 
    >> true )  
    Transcript written on test.log.

result with Metapost

    This is MetaPost, version 1.902 (TeX Live 2014) (kpathsea version 6.2.0)
    (/usr/local/texlive/2014/texmf-dist/metapost/base/mpost.mp
    (/usr/local/texlive/2014/texmf-dist/metapost/base/plain.mp
    Preloading the plain mem file, version 1.005) ) (./test.mf
    >> false )
    Transcript written on test.log.

Thanks T.