Initialize execStore while restoring a container from checkpoint.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)

daemon/daemon.go

@@ -165,7 +165,11 @@ func (daemon *Daemon) containerRoot(id string) string {
 // Load reads the contents of a container from disk
 // This is typically done at startup.
 func (daemon *Daemon) load(id string) (*Container, error) {
-	container := &Container{root: daemon.containerRoot(id), State: NewState()}
+	container := &Container{
+		root:         daemon.containerRoot(id),
+		State:        NewState(),
+		execCommands: newExecStore(),
+	}
 	if err := container.FromDisk(); err != nil {
 		return nil, err
 	}