bug#16871: Acknowledgement (problems about matching newline (with -z))

[Stephane Chazelas]

Also:

$ printf 'a\nb\0' | grep -z 'a$'
$ printf 'a\nb\0' | grep -zP 'a$'
a
b
$ printf 'a\nb\0' | grep -zxP a
a
b

Why use PCRE_MULTILINE here?