Subject: bug#18266: grep -P and invalid exits with error

From: Norihiro Tanaka <[email-masked]>
Date: Wed, 10 Sep 2014 08:39:10 +0900

I see that new version has no response for following test which was used
previously.

    printf '\x80ab\n' | env LC_ALL=en_US.utf8 src/grep -P '.?b'