fix(@schematics/angular): workaround bug in recorder/update

Author: filipesilva

packages/schematics/angular/migrations/update-8/differential-loading.ts

@@ -112,9 +112,21 @@ function updateBrowserlist(): Rule {
 
       const browserslistPath = join(normalize(project.root), 'browserslist');
       if (typeof project.sourceRoot === 'string') {
+        // Move the CLI 7 style browserlist to root if it's there.
         const srcBrowsersList = join(normalize(project.sourceRoot), 'browserslist');
-        if (tree.exists(srcBrowsersList)) {
-          tree.rename(srcBrowsersList, browserslistPath);
+        if (tree.exists(srcBrowsersList) && !tree.exists(browserslistPath)) {
+          // TODO: use rename instead.
+          // This is a hacky workaround. We should be able to just rename it.
+          // On unit tests the rename works fine but on real projects it fails with
+          //     ERROR! browserslist does not exist..
+          // This seems to happen because we are both renaming and then commiting an update.
+          // But it's fine if we read/create/delete. There's a bug somewhere.
+          // tree.rename(srcBrowsersList, browserslistPath);
+          const content = tree.read(srcBrowsersList);
+          if (content) {
+            tree.create(browserslistPath, content);
+            tree.delete(srcBrowsersList);
+          }
         }
       }