gitweb: shortlog now also obeys $hash_parent

If $hash_parent is defined, shortlog now limits the list of commits at
those between $hash_parent (exclusive) and $hash (inclusive).

Signed-off-by: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Acked-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index da474d0..18e70a3 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -5498,7 +5498,11 @@
 	}
 	my $refs = git_get_references();
 
-	my @commitlist = parse_commits($hash, 101, (100 * $page));
+	my $commit_hash = $hash;
+	if (defined $hash_parent) {
+		$commit_hash = "$hash_parent..$hash";
+	}
+	my @commitlist = parse_commits($commit_hash, 101, (100 * $page));
 
 	my $paging_nav = format_paging_nav('shortlog', $hash, $head, $page, $#commitlist >= 100);
 	my $next_link = '';