store option-invalue tuple only after successful set_option call - #696

connector: ldap.ldapobject.ReconnectLDAPObject
user_dn: str
password: str

(...)

try:
    # OPT_X_TLS_CRLCHECK is only valid for OpenSSL
    # connector.set_option stores the option-invalue tuple in connector._options
    # then attempts to set it with ReconnectLDAPObject.set_option
    connector.set_option(ldap.OPT_X_TLS_CRLCHECK, ldap.OPT_X_TLS_CRL_NONE)
except ValueError:
    # ReconnectLDAPObject.set_option raises a ValueError when using GnuTLS 
    # This Exception is expected and can be safely ignored
    pass

# OPT_X_TLD_CRLCHECK tuple is still stored in conn._options, 
# even if the ValueError was raised
(...)

try:
    # connecting to a Server that is down
    # this calls self._apply_method_s
    # which throws an ldap.SERVER_DOWN exception
    # which is handled within _apply_method_s by calling self.reconnect(..., force=True)
    # which calls self.restore_options
    # which calls self.set_option for the tuples in self._options
    # which raises ValueError
    connector.simple_bind_s(user_dn,password)
except ldap.SERVER_DOWN:
    # handle exception if the server is down
    pass
except ValueError:
    # this is should not have been raised here
    raise