URL.with_port() reencoding user/password

[elciok]

Describe the bug

When an URL already contains user and password, calling URL.to_path() is replacing special characters for strings that were already encoded.

To Reproduce

The second assert in the following snippet fails, but it should pass:

from yarl import URL

assert (
    str(URL("http://user%name:pass%word@localhost/"))
    == "http://user%25name:pass%25word@localhost/"
)
assert (
    str(URL("http://user%name:pass%word@localhost/").with_port(9000))
    == "http://user%25name:pass%25word@localhost:9000/"
)

Expected behavior

A URL user/password like "user%name" should be encoded as "user%25name", but calling to_path changes it to "user%2525name".

Logs/tracebacks

Traceback (most recent call last):
  File "/tmp/yarltesting.py", line 7, in <module>
    assert (
AssertionError

Python Version

$ python --version

Python 3.9.6

multidict Version

$ python -m pip show multidict

Name: multidict
Version: 5.1.0
Summary: multidict implementation
Home-page: https://github.com/aio-libs/multidict
Author: Andrew Svetlov
Author-email: andrew.svetlov@gmail.com
License: Apache 2
Location: /home/elciok/.cache/pypoetry/virtualenvs/archiver-6vV8vJQs-py3.9/lib/python3.9/site-packages
Requires: 
Required-by: yarl

yarl Version

$ python -m pip show yarl

Name: yarl
Version: 1.6.3
Summary: Yet another URL library
Home-page: https://github.com/aio-libs/yarl/
Author: Andrew Svetlov
Author-email: andrew.svetlov@gmail.com
License: Apache 2
Location: /home/elciok/.cache/pypoetry/virtualenvs/archiver-6vV8vJQs-py3.9/lib/python3.9/site-packages
Requires: idna, multidict

OS

$ lsb_release -a

LSB Version: core-9.20170808ubuntu1-noarch:printing-9.20170808ubuntu1-noarch:security-9.20170808ubuntu1-noarch
Distributor ID: Ubuntu
Description: Ubuntu 18.04.5 LTS
Release: 18.04
Codename: bionic

Additional context

No response

Code of Conduct

• I agree to follow the aio-libs Code of Conduct

[asvetlov]

We need a champion for the bug. Please feel free to create a Pull Request