Provisionally stop working around issues 9252 and 9253.

utils/pub/hosted_source.dart

Index: utils/pub/hosted_source.dart
diff --git a/utils/pub/hosted_source.dart b/utils/pub/hosted_source.dart
index 00e489b7bfe65fef9e90a0fc3f576f78600e16ae..bb4345c0761817aaa1a08697f1b3d2da63a7b1e9 100644
--- a/utils/pub/hosted_source.dart
+++ b/utils/pub/hosted_source.dart
@@ -82,8 +82,9 @@ class HostedSource extends Source {
         // Now that the install has succeeded, move it to the real location in
         // the cache. This ensures that we don't leave half-busted ghost
         // directories in the user's pub cache if an install fails.
-        return renameDir(tempDir, destPath);
-      }).then((_) => true);
+        renameDir(tempDir, destPath);
+        return true;
+      });
     });
   }