Can't get messages from MessageGenerator

[lucaspg96]

I'm trying to implement some tests to a bot that I'm constructing and I got the following error:

"TypeError: init() missing 1 required positional argument: 'is_bot' "

Also, I cloned your repo and ran your tests. You got the same error. That is the configuration of my environment:

certifi==2016.2.28
click==6.7
Flask==0.12.2
future==0.16.0
itsdangerous==0.24
Jinja2==2.9.6
MarkupSafe==1.0
ptbtest==1.3
pymongo==3.4.0
python-telegram-bot==8.1.1
Werkzeug==0.12.2

The error happens when calling the get_message() method.