[PATCH] gitweb: Fix "Use of uninitialized value" warning in git_feed

[Jakub Narebski <jnareb@gmail.com>]

Initial (root) commit has no parents, and $co{'parent'} is
undefined. Use '--root' for initial commit.

This fixes "Use of uninitialized value in open at gitweb/gitweb.perl
line 4925." warning.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
---
 gitweb/gitweb.perl |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index fa8cc02..091cf9c 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -4923,7 +4923,8 @@ XML
 
 		# get list of changed files
 		open my $fd, "-|", git_cmd(), "diff-tree", '-r', @diff_opts,
-			$co{'parent'}, $co{'id'}, "--", (defined $file_name ? $file_name : ())
+			$co{'parent'} || "--root",
+			$co{'id'}, "--", (defined $file_name ? $file_name : ())
 			or next;
 		my @difftree = map { chomp; $_ } <$fd>;
 		close $fd
-- 
1.5.1.4