Partially encoded parameter

[edbentley]

Version

4.2.0

Test Case

https://codesandbox.io/s/qxv30r58m6

Steps to reproduce

1. My app has an id string that is partially encoded, e.g. id//github%2Fissues
2. I encode this (using encodeURIComponent) to id%2F%2Fgithub%252Fissues in the URL.
   <Link to='/id%2F%2Fgithub%252Fissues'>link</Link>
   It is still encoded in the address bar.
3. Use a path of /:id
4. I then receive this back as parameter match.params.id which when printed out is id%2F%2Fgithub%2Fissues (note %252F has become %2F - looks like decodeURI was run on it)
5. I decode it (using decodeURIComponent) and get id//github/issues back

Expected: id//github%2Fissues
Actual: id//github/issues

I was using koa router and this worked as expected, but refactoring to react router is causing this issue. Can this be fixed, or is there a way to disable what looks like decodeURI in step 4? I cannot get my original id back.

[timdorr]

Related to #5474.
Duplicate of remix-run/history#505.