Version

2.6.0

Reproduction link

https://codesandbox.io/embed/vue-template-hf9hq

Steps to reproduce

• Click on 'route' link
• Look at the console

What is expected?

In components/Parent.vue the object childRoute, that is passed as the to prop of <router-link>, should not be mutated.

What is actually happening?

It is mutated (the key parent is added to childRoute.params)