[XeTeX] ifcat changed?

[Bruno Le Floch]

Dear all,

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

It would be useful for me to know which of \ifcat, \relax, and \cr
changed, to determine whether I should just special-case \cr in my
package, or use some other tool than \ifcat.

Best regards,

Bruno