'Decides whether a line should be copied to a SSL vhost.
A canonical example of when sifting a line is required:
When the http vhost contains a RewriteRule that unconditionally
redirects any request to the https version of the same site.
e.g:
RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [L,QSA,R=permanent]
Copying the above line to the ssl vhost would cause a
redirection loop.
:param str line: a line extracted from the http vhost.
:returns: True - don\'t copy line from http vhost to SSL vhost.
:rtype: bool'

def _sift_rewrite_rule(self, line):

    if (not line.lower().lstrip().startswith('rewriterule')):
        return False
    target = line.split()[2].strip()
    if ((target[0] in ("'", '"')) and (target[0] == target[(-1)])):
        target = target[1:(-1)]
    return target.startswith('https://')
