gitweb: Harden "grep" search against filenames with ':'

Run "git grep" in "grep" search with '-z' option, to be able to parse
response also for files with filename containing ':' character.  The
':' character is otherwise (without '-z') used to separate filename
from line number and from matched line.

Note that this does not protect files with filename containing
embedded newline.  This would be hard but doable for text files, and
harder or even currently impossible with binary files: git does not
quote filename in

  "Binary file <foo> matches"

message, but new `--break` and/or `--header` options to git-grep could
help here.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/gitweb.perl

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 1d2f046..08020b0 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -5699,7 +5699,7 @@
 	my %co = @_;
 
 	local $/ = "\n";
-	open my $fd, "-|", git_cmd(), 'grep', '-n',
+	open my $fd, "-|", git_cmd(), 'grep', '-n', '-z',
 		$search_use_regexp ? ('-E', '-i') : '-F',
 		$searchtext, $co{'tree'}
 			or die_error(500, "Open git-grep failed");
@@ -5721,7 +5721,8 @@
 			$file = $1;
 			$binary = 1;
 		} else {
-			(undef, $file, $lno, $ltext) = split(/:/, $line, 4);
+			($file, $lno, $ltext) = split(/\0/, $line, 3);
+			$file =~ s/^$co{'tree'}://;
 		}
 		if ($file ne $lastfile) {
 			$lastfile and print "</td></tr>\n";