letphivarphi

documentclass[a4paper]{article}
usepackage{fontspec}
usepackage{unicode-math}

%setmathfont{MnSymbol}
%setmathfont[range=mathit/{num,latin,Latin,greek,Greek}]{MinionPro-It}

letphivarphi
letepsilonvarepsilon

begin{document}

noindent
varphi: $varphi$ works!\
phi: $phi$ should look the same, but does not!\
I actually want to fix the missing epsilon in MinionPro:\
varepsilon: $varepsilon$ works!\
epsilon: $epsilon$ doesn't!\

end{document}