title: canvas background turns black after rerender fabric.js
body: <p>I have the following situation: I draw the canvas with a background image and this works:</p>
  
  <pre><code>var canvasSection = new fabric.Canvas('buildSection', {
    selectionColor: 'rgba(94,213,94,0.2)',
    width: widthS,
    height: heightS,
    hoverCursor: 'pointer',
    backgroundColor: ({
      source: 'image/bordenconfigurator/background/background1.png',
      repeat: 'repeat'
    })
  
  });
  </code></pre>
  
  <p>But then I need to clear canvas and to redraw it. at this point when I try to set background, instead of an image I see a black screen. In console I can see that the background image is set however. This is the code I'm trying:</p>
  
  <pre><code>$('#cForm').on('change', function() {
  
    if ($(this).val() == 'rectLandsc') {
      widthS = 600;
      heightS = 400;
  
    } else if ($(this).val() == 'rectPortr') {
      ....
  
    }
    canvasSection.clear();
  
    canvasSection.set({
      fill: 'rgba(0,0,0,0)',
      //  backgroundColor: ({source: 'image/bordenconfigurator/background/background1.png', repeat: 'repeat'})
    });
    //canvasSection.backgroundColor({source: 'image/bordenconfigurator/background/background.png', repeat:'repeat'});
    canvasSection.setBackgroundColor({
        source: 'image/bordenconfigurator/background/background.png'
      }),
      canvasSection.renderAll.bind(canvas);
    drawBaseForm();
    canvasSection.renderAll();
  
    console.log(canvasSection);
  });
  </code></pre>
  
  <p>Is it a kind of a bug? Or am I doing something wrong? Could anyone help me out here?</p>