assert fail in ChangeCurrentAvailInfo

[kcwu]

original report https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=146

How to reproduce

$ ./autogen.sh
$ ./configure
$ make clean check
$ ./test/stress -loop 1 -extra -verbose -file 146-assert
stress: choice.c:529: ChoiceEndChoice: Assertion `pgdata->chiSymbolCursor <= pgdata->chiSymbolBufLen' failed.

reduced test case

$ xxd 146-assert
00000000: 3030 3030 3030 3006 c406 303c            0000000...0<