/say command removes %s, %d, %1-9

How to reproduce

/say %a %s %d %1 %2 %3 %4 %5 %6 %7 %8 %9 %z

Expected result
It outputs exactly what you typed

Actual result
Only %a and %z show up

Notes
The percent codes are used for localization insertions, but /say is not localized so they should not be parsed in that command at all.