[PATCH] Avoid errors from git-rev-parse in gitweb blame

[Rafael Garcia-Suarez <rgarciasuarez@gmail.com>]

git-rev-parse will abort with an error when passed a non-existent
revision spec, such as "deadbeef^" where deadbeef has no parent.
Using the --revs-only parameter makes this error go away, while
retaining functionality, keeping the web server error log nice
and clean.

Signed-off-by: Rafael Garcia-Suarez <rgarciasuarez@gmail.com>
---
 gitweb/gitweb.perl |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 55fb100..f3b4b24 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -4226,9 +4226,9 @@ HTML
 			              esc_html($rev));
 			print "</td>\n";
 		}
-		open (my $dd, "-|", git_cmd(), "rev-parse", "$full_rev^")
+		open (my $dd, "-|", git_cmd(), "rev-parse", '--revs-only', "$full_rev^")
 			or die_error(undef, "Open git-rev-parse failed");
-		my $parent_commit = <$dd>;
+		my $parent_commit = <$dd> || '';
 		close $dd;
 		chomp($parent_commit);
 		my $blamed = href(action => 'blame',
-- 
1.5.6.rc1