gitweb: Do not show difftree for merges in "commit" view

Do not show difftree against first parent for merges (commits with
more than one parent) in "commit" view, because it usually is
misleading.  git-show and git-whatchanged doesn't show diff for merges
either.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 040ee719f0df34f948871670e9a8936fd73eb327..ebf35a1e2bc10002486d45e3796a4f2f336dca8a 100755 (executable)
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -3572,14 +3572,19 @@ sub git_commit {
        my %cd = parse_date($co{'committer_epoch'}, $co{'committer_tz'});
 
        my $parent = $co{'parent'};
+       my $parents = $co{'parents'};
        if (!defined $parent) {
                $parent = "--root";
        }
-       open my $fd, "-|", git_cmd(), "diff-tree", '-r', "--no-commit-id",
-               @diff_opts, $parent, $hash, "--"
-               or die_error(undef, "Open git-diff-tree failed");
-       my @difftree = map { chomp; $_ } <$fd>;
-       close $fd or die_error(undef, "Reading git-diff-tree failed");
+       my @difftree;
+       if (@$parents <= 1) {
+               # difftree output is not printed for merges
+               open my $fd, "-|", git_cmd(), "diff-tree", '-r', "--no-commit-id",
+                       @diff_opts, $parent, $hash, "--"
+                               or die_error(undef, "Open git-diff-tree failed");
+               @difftree = map { chomp; $_ } <$fd>;
+               close $fd or die_error(undef, "Reading git-diff-tree failed");
+       }
 
        # non-textual hash id's can be cached
        my $expires;
@@ -3641,7 +3646,7 @@ sub git_commit {
        }
        print "</td>" .
              "</tr>\n";
-       my $parents = $co{'parents'};
+
        foreach my $par (@$parents) {
                print "<tr>" .
                      "<td>parent</td>" .
@@ -3663,7 +3668,10 @@ sub git_commit {
        git_print_log($co{'comment'});
        print "</div>\n";
 
-       git_difftree_body(\@difftree, $hash, $parent);
+       if (@$parents <= 1) {
+               # do not output difftree/whatchanged for merges
+               git_difftree_body(\@difftree, $hash, $parent);
+       }
 
        git_footer_html();
 }