Fix absolute path importing in sass (#2432)

packages/core/integration-tests/test/integration/scss-absolute-imports/b.scss

@@ -0,0 +1,3 @@
+.b {
+  color: red;
+}

packages/core/integration-tests/test/integration/scss-absolute-imports/style.scss

@@ -0,0 +1,5 @@
+@import '/b.scss';
+
+.a {
+  color: blue;
+}

packages/core/integration-tests/test/sass.js

@@ -228,4 +228,22 @@ describe('sass', function() {
     assert(css.includes('.foo { color: blue;'));
     assert(css.includes('.bar { color: green;'));
   });
+
+  it('should support absolute imports', async function() {
+    let b = await bundle(
+      path.join(__dirname, '/integration/scss-absolute-imports/style.scss')
+    );
+
+    await assertBundleTree(b, {
+      name: 'style.css',
+      assets: ['style.scss']
+    });
+
+    let css = await fs.readFile(
+      path.join(__dirname, '/dist/style.css'),
+      'utf8'
+    );
+    assert(css.includes('.a'));
+    assert(css.includes('.b'));
+  });
 });

packages/core/parcel-bundler/src/assets/SASSAsset.js

@@ -45,6 +45,7 @@ class SASSAsset extends Asset {
       ? opts.importer
       : [opts.importer];
     opts.importer.push((url, prev, done) => {
+      url = url.replace(/^file:\/\//, '');
       url = parseCSSImport(url);
       resolver
         .resolve(url, prev === 'stdin' ? this.name : prev)