**Describe the bug**
When using https://github.com/axios/axios/pull/1712 example and adding baseURL in config, baseURL seems to not be used.

**To Reproduce**

```js
const axios = require("axios");
const fakeConfig = {
  method: "post",
  url: "/user/12345",
  baseURL: "/foo"
};
console.log(axios.getUri(fakeConfig));
```

**Expected behavior**
`axios.getUri` should return `/foo/user/12345`.

If this expected behavior seems right, I can work on a fix.

**Environment:**
 - Axios Version: 0.19.0
 - OS: Linux, Windows
 - Browser Chrome but also happen on Firefox and node
lib/core/Axios.js
responseInterceptorChain.push(interceptor.fulfilled, interceptor.rejected);
  });
  var promise;
  if (!synchronousRequestInterceptors) {
    var chain = [dispatchRequest, undefined];
    Array.prototype.unshift.apply(chain, requestInterceptorChain);
    chain = chain.concat(responseInterceptorChain);
    promise = Promise.resolve(config);
    while (chain.length) {
      promise = promise.then(chain.shift(), chain.shift());
    }
    return promise;
  }
  var newConfig = config;
  while (requestInterceptorChain.length) {
    var onFulfilled = requestInterceptorChain.shift();
    var onRejected = requestInterceptorChain.shift();
    try {
      newConfig = onFulfilled(newConfig);
    } catch (error) {
      onRejected(error);
      break;
    }
  }
  try {
    promise = dispatchRequest(newConfig);
  } catch (error) {
    return Promise.reject(error);
  }
  while (responseInterceptorChain.length) {