bash tries to parse comsub in quoted PE pattern

[Emanuele Torre]

In a PE pattern, if the pattern has a single quoted part that contains
 $(  and does not contain a closing parenthesis, and has  \'  at the
end, bash will try to parse a command substitution and fail.

    $ echo "${HOME#'$('\'}"
    bash: command substitution: line 3: unexpected EOF while looking for 
matching `"'
    $ echo "${HOME#aaaa'$(aaaa'aaa)aaa\'}"
    bash: command substitution: line 5: unexpected EOF while looking for 
matching `"'
    $ echo "${HOME#aaaa'$(aaaa)'aaaa\'}"
    /home/emanuele6

I was able to reprodcue this bug in all versions starting from bash 4.3.

o/
 emanuele6