Encoded strings and uwsgi magic variables

URL encoded strings (AKA URL Quoting in python) don't well play inside configuration files (*.ini files).
The issues lies in strings containing sequences chars matching to chars in the magic table of configuration placeholders.
It leads to issues like urlencoded strings (i.g.: passwords) being modified by uwsgi process. Real (and common usage) exemple:
Given a environmwent varible like DSN=amqp://admin:ABC_%3F@localhost:5972 and placed at uwsgi.ini, when I run the application it's expected to get (i.g.: os.environ['DSN']) the string amqp://admin:ABC_%3F@localhost:5972.
However, the returned string is something like this: amqp://admin:ABC_tmpF@localhost:5972
Because %3 (from string ABC_%3F) is a reserved placeholder (see magic vars), it corresponds to a specific component of the full path of the directory containing the config file - in my case, tmp/ dir.

Setup and requirements

• Python v2.7
• uwsgi v2.0.18
• any web framework wsgi compatible (such as flask or django)

Installing minimum requirements:

# cd into this repository directory
python -m venv
./venv/bin/activate
pip install -r requirements.txt
# run application
uwsgi --ini uwsgi.ini