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 <redacted>
Signed-off-by: Junio C Hamano <redacted>

diff --git a/gitweb.perl b/gitweb.perl
index 67af826c9f46bc234dcc916af323a102b4c5e38721ee910e0950230109046543..421727daab97d4b8c36f631fe8ddb9b95e88a21d93fc204972f87c7c26470764 100755 (executable)
--- a/gitweb.perl
+++ b/gitweb.perl
@@ -3573,14 +3573,19 @@ 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;
@@ -3642,7 +3647,7 @@ sub git_commit {
        }
        print "</td>" .
              "</tr>\n";
-       my $parents = $co{'parents'};
+
        foreach my $par (@$parents) {
                print "<tr>" .
                      "<td>parent</td>" .
@@ -3664,7 +3669,10 @@ 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();
 }