雪碧图打包调整

@@ -39,6 +39,9 @@ const dist = {
     font: `${distRoot}/assets/font`
 };
 
+// webpack 内嵌的样式中的雪碧图，写文件的时候会有冲突，这边使用单实例
+let postcssSprites;
+
 /**
  * postcss plugins for both dev and pro
  * @parem et Symbol
@@ -93,9 +96,12 @@ const postcssPlugin = (et) => {
         });
     }
 
+    if (!postcssSprites) {
+        postcssSprites = require('postcss-sprites').default(sprites);
+    }
     plugins = [
         require('precss'),
-        require('postcss-sprites').default(sprites),
+        postcssSprites,
         require('postcss-assets')(assets),
         require('postcss-calc'),
         require('postcss-pxtorem')({