daemon: Daemon.initializeNetworking: remove var declaration

The function was declaring an err variable which was shadowed. It was
intended for directly assigning to a struct field, but as this function
is directly mutating an existing object, and the err variable was declared
far away from its use, let's use an intermediate var for that to make it
slightly more atomic.

While at it, also combined two "if" branches.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

daemon/container_operations.go

@@ -948,8 +948,6 @@ func (daemon *Daemon) tryDetachContainerFromClusterNetwork(network *libnetwork.N
 }
 
 func (daemon *Daemon) initializeNetworking(cfg *config.Config, container *container.Container) error {
-	var err error
-
 	if container.HostConfig.NetworkMode.IsContainer() {
 		// we need to get the hosts files from the container to join
 		nc, err := daemon.getNetworkedContainer(container.ID, container.HostConfig.NetworkMode.ConnectedContainer())
@@ -967,13 +965,12 @@ func (daemon *Daemon) initializeNetworking(cfg *config.Config, container *contai
 		return nil
 	}
 
-	if container.HostConfig.NetworkMode.IsHost() {
-		if container.Config.Hostname == "" {
-			container.Config.Hostname, err = os.Hostname()
-			if err != nil {
-				return err
-			}
+	if container.HostConfig.NetworkMode.IsHost() && container.Config.Hostname == "" {
+		hn, err := os.Hostname()
+		if err != nil {
+			return err
 		}
+		container.Config.Hostname = hn
 	}
 
 	if err := daemon.allocateNetwork(cfg, container); err != nil {