[XeTeX] ifcat changed?

[Julian Bradfield]

On 2017-04-15, Bruno Le Floch <blflatex at gmail.com> wrote:
> The primitive conditional "\ifcat\relax\cr true\else false\fi" gives
> "true" in pdfTeX, LuaTeX, (e)(u)pTeX, and XeTeX from some time ago
> (could be years), but "false" in XeTeX 0.99996

Definitely a bug. The TeXbook defines the behaviour of \if and \ifcat,
and all control sequences are considered to have character code 256
and category code 16, unless \let equal to a non-active character, in
which case they have the value of that character.