Fix bad argument to iscsiadm in iSCSI discovery

Fix a call to _iscsiadm_update() in which a list was being passed as
the target_iqn connection property.  This property is used directly as
an argument to the iscsiadm -T option, so it must be a plain string.

Change-Id: I9c2ff1de1f89fb49dd6c5a90679d5c4238d5476a
Closes-bug: 1838820

os_brick/initiator/connectors/iscsi.py

@@ -1178,7 +1178,7 @@ class ISCSIConnector(base.BaseLinuxConnector, base_iscsi.BaseISCSIConnector):
                 # as discovering target.
                 # So target_iqn is updated, and other values aren't updated.
                 recover_connection = copy.deepcopy(connection_properties)
-                recover_connection['target_iqn'] = [iqn]
+                recover_connection['target_iqn'] = iqn
                 self._iscsiadm_update(recover_connection,
                                       "node.startup",
                                       old_node_startup)

os_brick/tests/initiator/connectors/test_iscsi.py

@@ -1665,8 +1665,8 @@ Setting up iSCSI targets: unused
         iqn1 = 'iqn.2010-10.org.openstack:%s' % name1
         iqn2 = 'iqn.2010-10.org.openstack:%s' % name2
         iqn3 = 'iqn.2010-10.org.openstack:%s' % name3
-        connection_properties = self.iscsi_connection(vol, [location], [iqn1])
-        recover_connection = self.iscsi_connection(vol, [location], [iqn2])
+        connection_properties = self.iscsi_connection(vol, [location], iqn1)
+        recover_connection = self.iscsi_connection(vol, [location], iqn2)
 
         node_startup1 = "manual"
         node_startup2 = "automatic"