_qv_basename() returns urlencoded string

[scribu]

In [16155] I replaced _qv_basename() with wp_basename().

In _qv_basename(), urldecode() is called before urlencode(), while in wp_basename() it's called after.

I consider the behaviour in _qv_basename() a bug, since there's no urlencode() being called before that.

This ticket is for reporting any issues that might arise from this change.