Assertion fail report: src/parse-gram.c:3268

Hello,
I report an assertion failure test input generated during a fuzzing test.

src/parse-gram.c:3268: char *unquote(const char *): Assertion `*cp == '"''
failed.

I test on the latest revision of bison uploaded on git.
You can reproduce the failure by
./bison <test input>

Thank you,
Ahcheong Lee
---------------------------------------------
Ahcheong Lee, Master's student
School of Computing, KAIST
Room# 2438, E3-1, KAIST
373-1 Guseong-dong, Yuseong-gu
Daejeon, South Korea 34141
Phone: 010-7350-3811
------------------------------------------------