t / t3901-8859-1.txton commit grep: add a test asserting that --perl-regexp dies when !PCRE (9001c19)
   1: to be sourced in t3901 -- this is latin-1
   2GIT_AUTHOR_NAME="Áéí óú" &&
   3GIT_COMMITTER_NAME=$GIT_AUTHOR_NAME &&
   4export GIT_AUTHOR_NAME GIT_COMMITTER_NAME