Fix application of network --mtu kickstart option in Anaconda

This was broken when application of kickstart network command was moved
to Anaconda.

Resolves: rhbz#2018301

pyanaconda/modules/network/nm_client.py

@@ -418,6 +418,8 @@ def create_connections_from_ksdata(nm_client, network_data, device_name, ifname_
             s390cfg = get_s390_settings(device_name)
             _update_wired_connection_with_s390_settings(con, s390cfg)
 
+    update_connection_wired_settings_from_ksdata(con, network_data)
+
     connections.insert(0, (con, device_to_activate))
 
     return connections
@@ -577,6 +579,8 @@ def update_connection_from_ksdata(nm_client, connection, network_data, device_na
     # IP configuration
     update_connection_ip_settings_from_ksdata(connection, network_data)
 
+    update_connection_wired_settings_from_ksdata(connection, network_data)
+
     s_con = connection.get_setting_connection()
     s_con.set_property(NM.SETTING_CONNECTION_AUTOCONNECT, network_data.onboot)
 
@@ -655,6 +659,27 @@ def update_connection_ip_settings_from_ksdata(connection, network_data):
                 log.error("IP address %s is not valid", ns)
 
 
+def update_connection_wired_settings_from_ksdata(connection, network_data):
+    """Update NM connection wired settings from kickstart in place.
+
+    :param connection: existing NetworkManager connection to be updated
+    :type connection: NM.RemoteConnection
+    :param network_data: kickstart configuation to be applied to the connection
+    :type network_data: pykickstart NetworkData
+    """
+    if network_data.mtu:
+        try:
+            mtu = int(network_data.mtu)
+        except ValueError as e:
+            log.error("Value of network --mtu option is not valid: %s", network_data.mtu)
+        else:
+            s_wired = connection.get_setting_wired()
+            if not s_wired:
+                s_wired = NM.SettingWired.new()
+                connection.add_setting(s_wired)
+            s_wired.props.mtu = mtu
+
+
 def bind_settings_to_mac(nm_client, s_connection, s_wired, device_name=None, bind_exclusively=True):
     """Bind the settings to the mac address of the device.
 

tests/nosetests/pyanaconda_tests/module_network_nm_client_test.py

@@ -21,7 +21,7 @@
 from unittest.mock import Mock, patch
 
 from pyanaconda.modules.network.nm_client import get_slaves_from_connections, \
-    get_dracut_arguments_from_connection
+    get_dracut_arguments_from_connection, update_connection_wired_settings_from_ksdata
 
 import gi
 gi.require_version("NM", "1.0")
@@ -482,3 +482,38 @@ def get_dracut_arguments_from_connection_test(self, is_s390, get_slaves_from_con
                  "vlan=ens13.111:ens13",
                  "rd.znet=qeth,0.0.0900,0.0.0901,0.0.0902,layer2=1,portname=FOOBAR,portno=0"])
         )
+
+    def update_connection_wired_settings_from_ksdata_test(self):
+        network_data = Mock()
+        connection = Mock()
+        wired_setting = Mock()
+
+        connection.get_setting_wired.return_value = wired_setting
+
+        # --mtu default value
+        network_data.mtu = ""
+        update_connection_wired_settings_from_ksdata(connection, network_data)
+        connection.get_setting_wired.assert_not_called()
+
+        # Invalid value
+        # --mtu=non-int
+        network_data.mtu = "non-int"
+        connection.reset_mock()
+        update_connection_wired_settings_from_ksdata(connection, network_data)
+        connection.get_setting_wired.assert_not_called()
+
+        # Valid value
+        # --mtu=9000
+        # The connection already has wired setting
+        connection.reset_mock()
+        network_data.mtu = "9000"
+        update_connection_wired_settings_from_ksdata(connection, network_data)
+        connection.get_setting_wired.assert_called_once()
+
+        # Valid value
+        # --mtu=9000
+        # The connection does not have wired setting yet
+        connection.get_setting_wired.return_value = None
+        connection.reset_mock()
+        update_connection_wired_settings_from_ksdata(connection, network_data)
+        connection.add_setting.assert_called_once()