parsers.c: parse_manifest: fixing refcount of flags
When flags was DECREF'ed, scope was referencing to the outer variable,
outside of the block.
It was in fact always NULL: the real Python object was never decref'ed.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US">
<head>
<link rel="icon" href="{staticurl}hgicon.png" type="image/png" />
<meta name="robots" content="index, nofollow" />
<link rel="stylesheet" href="{staticurl}style-paper.css" type="text/css" />