rerere: avoid open "-|" list form for Perl 5.6

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/git-rerere.perl b/git-rerere.perl
index df11951..d3664ff 100755 (executable)
--- a/git-rerere.perl
+++ b/git-rerere.perl
@@ -131,7 +131,11 @@ sub record_preimage {
 sub find_conflict {
        my $in;
        local $/ = "\0";
-       open $in, '-|', qw(git ls-files -z -u) or die "$!: ls-files";
+       my $pid = open($in, '-|');
+       die "$!" unless defined $pid;
+       if (!$pid) {
+               exec(qw(git ls-files -z -u)) or die "$!: ls-files";
+       }
        my %path = ();
        my @path = ();
        while (<$in>) {