Steps to reproduce

1.Connection errors

1. the user and pass is given in that format:

https_proxy=user:pass@proxydir:port

http_proxy=user:pass@proxydir:port
3.

Expected behaviour

Tell us what should happen

Actual behaviour

Tell us what happens instead

Configuration

Debian "stretch"

Version of Python:

$ python -Vver 3.5

Version of python-telegram-bot:
4.3.3
$ python -c 'import telegram; print(telegram.__version__)'

Logs

Insert logs here (if necessary)