Calling `validate_sign` with both `cert` and `multicerts` should not ignore `cert`

[networkException]

When providing both a value for cert and multicerts to

python-saml/src/onelogin/saml2/utils.py

Line 965 in 488a00d

def validate_sign(xml, cert=None, fingerprint=None, fingerprintalg='sha1', validatecert=False, debug=False, xpath=None, multicerts=None):

the branching will ignore the value given for cert

python-saml/src/onelogin/saml2/utils.py

Lines 1042 to 1048 in 488a00d

	# If multiple certs are provided, I may ignore cert and
	# fingerprint provided by the method and just check the
	# certs multicerts
	fingerprint = fingerprintalg = None
	for cert in multicerts:
	if OneLogin_Saml2_Utils.validate_node_sign(signature_node, elem, cert, fingerprint, fingerprintalg, validatecert, False, raise_exceptions=False):
	return True

While reading the code / comment clarifies this behavior, the parameter documentation doesn't mention it making this function behave somewhat unexpected leading to security issues at worst.