Using right click on a horse with a saddle in hand crashes client

When we try to right click a horse, with a saddle in hand, the client crashes with
Client> java.io.IOException: Received string length longer than maximum allowed (33 > 32)
Client> at ex.a(SourceFile:240)
Client> at dv.a(SourceFile:52)
Client> at ex.a(SourceFile:197)
Client> at cn.i(SourceFile:249)
Client> at cn.c(SourceFile:17)
Client> at co.run(SourceFile:94)

An almost identical error happens when we mount a horse, and use "e" to see inventory and put on the saddle.

The horse was tamed and not named with a nametag