Why isn't my Pygame/OpenGL game background working when I've tried pygame.image.load and pygame.transform.scale?

Question

Im trying to add background to my pygame/opengl game. But I cannot do it and i do not understand why.

I tried doing this

bg_img = pygame.image.load('./textures/background_image.jpg')
bg_img = pygame.transform.scale(bg_img, display)
window.blit(bg_img, (0, 0))

but it doesnt work, and i dont know why.

    def draw_map(self):
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
        glLoadIdentity()

        glTranslatef(self.xtrans, self.ytrans, -5.0 * self.zoom)
        glRotatef(self.xrot, 1.0, 0.0, 0.0)
        glRotatef(self.yrot, 0.0, 1.0, 0.0)

        glBegin(GL_LINES)
        for point in self.tree.map:
            for i, connection in enumerate(point.connections):
                glColor3f(1.0, 1.0, 1.0)
                glVertex3f(point.x, point.y, point.z)
                glVertex3f(self.tree.map[connection].x, self.tree.map[connection].y, self.tree.map[connection].z)
        glEnd()

        glPointSize(10)
        glBegin(GL_POINTS)
        for agent in self.agents:
            glColor3f(1.0, 0.0, 0.0)
            position = self.tree.map[agent.position]
            glVertex3f(position.x, position.y, position.z)
        glEnd()

        glPointSize(20)
        glBegin(GL_POINTS)
        for point in self.tree.map:
            glColor3f(1.0, 1.0, 1.0)
            glVertex3f(point.x, point.y, point.z)
        glEnd()

        pygame.display.flip()



    def run(self):
        pygame.init()
        display = (800, 600)
        window = pygame.display.set_mode(display, DOUBLEBUF | OPENGL)
        pygame.display.set_caption("Geco")


        glMatrixMode(GL_PROJECTION)
        gluPerspective(45, (display[0] / display[1]), 0.1, 50.0)

        glMatrixMode(GL_MODELVIEW)
        glEnable(GL_DEPTH_TEST)

        clock = pygame.time.Clock()

        while True:
            self.handle_events()
            for event in pygame.event.get():
                if event.type == pygame.QUIT:
                    pygame.quit()
                    quit()


            bg_img = pygame.image.load('./textures/background_image.jpg')
            bg_img = pygame.transform.scale(bg_img, display)
            window.blit(bg_img, (0, 0))

            self.draw_map()
            clock.tick(60)

Here is the code. As far as i understand problem can be that opengl is rendering window, not pygame, so pygame functions wont affect anything. Im not sure how to fix it. Thank you for helping in advance.