- 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");
+ }