[tex-live] recent texlive 2015 update causes unicode-math error

[David Carlisle]

The fix for this is in the unicode-math github, so I guess Will will
push an update to ctan as soon as he's back from TUG2015, meanwhile as
a temporary fix you can restore the deprecated command by adding the
following before loading unicode-math

\usepackage{expl3}
\ExplSyntaxOn \cs_set_eq:NN \tl_case:Nnn \tl_case:NnF \ExplSyntaxOff

David