repobrowse: show roughly equivalent "diff-tree" invocation

This will make it easier to show how the diff output
was generated and hopefully teach users to use the
git command-line.

1 files changed, 7 insertions, 4 deletions

diff --git a/lib/PublicInbox/RepobrowseGitDiff.pm b/lib/PublicInbox/RepobrowseGitDiff.pm
index 8e535708..8c349e9b 100644
--- a/lib/PublicInbox/RepobrowseGitDiff.pm
+++ b/lib/PublicInbox/RepobrowseGitDiff.pm
@@ -27,9 +27,8 @@ sub call_git_diff {
         my @cmd = (qw(diff-tree -z --numstat -p --encoding=UTF-8
                         --no-notes --no-color -M -B -D -r),
                         $id2, $id, '--');
-        if (defined(my $expath = $req->{expath})) {
-                push @cmd, $expath;
-        }
+        my $expath = $req->{expath};
+        push @cmd, $expath if defined $expath;
         $req->{rpipe} = $git->popen(\@cmd, undef, { 2 => $git->err_begin });
         my $env = $req->{cgi}->env;
         my $err = $env->{'psgi.errors'};
@@ -74,7 +73,11 @@ sub call_git_diff {
                         my $h = ['Content-Type', 'text/html; charset=UTF-8'];
                         my $fh = $req->{fh} = $res->([200, $h]);
                         my $o = { nofollow => 1, noindex => 1 };
-                        $fh->write($self->html_start($req, 'diff', $o)."\n");
+                        my $ex = defined $expath ? " $expath" : '';
+                        $fh->write($self->html_start($req, 'diff', $o).
+                                        "\n\n".
+                                        utf8_html("git diff-tree -r -M -B -D ".
+                                                "$id2 $id --$ex"). "\n\n");
                 }
                 if (my $fh = $req->{fh}) {
                         git_diff_to_html($req, $fh);