Exchange the check order for the dhcp and no-dhcp

The dhcp is setting with True by default and progress always
jump into the first if check.
So the no-dhcp option always ignored there.

Check the no-dhcp option first and then the dhcp option value
to avoid this.

Change-Id: Ide640e2cab3936d419ca62105304ff5d4a8a2074
Closes-Bug: #1602588

Author: qiangtang

openstackclient/network/v2/subnet.py

@@ -168,7 +168,7 @@ def _get_attrs(client_manager, parsed_args, is_create=True):
         attrs['allocation_pools'] = parsed_args.allocation_pools
     if parsed_args.dhcp:
         attrs['enable_dhcp'] = True
-    elif parsed_args.no_dhcp:
+    if parsed_args.no_dhcp:
         attrs['enable_dhcp'] = False
     if ('dns_nameservers' in parsed_args and
        parsed_args.dns_nameservers is not None):
@@ -223,7 +223,6 @@ def get_parser(self, prog_name):
         dhcp_enable_group.add_argument(
             '--dhcp',
             action='store_true',
-            default=True,
             help=_("Enable DHCP (default)")
         )
         dhcp_enable_group.add_argument(

openstackclient/tests/network/v2/test_subnet.py

@@ -236,7 +236,6 @@ def test_create_default_options(self):
 
         self.network.create_subnet.assert_called_once_with(**{
             'cidr': self._subnet.cidr,
-            'enable_dhcp': self._subnet.enable_dhcp,
             'ip_version': self._subnet.ip_version,
             'name': self._subnet.name,
             'network_id': self._subnet.network_id,
@@ -410,7 +409,6 @@ def test_create_with_network_segment(self):
 
         self.network.create_subnet.assert_called_once_with(**{
             'cidr': self._subnet.cidr,
-            'enable_dhcp': self._subnet.enable_dhcp,
             'ip_version': self._subnet.ip_version,
             'name': self._subnet.name,
             'network_id': self._subnet.network_id,