Endless loop incompatible when I pip install requirements (Django1.99)
As far as I can see you have the following options:

Run pip with the --no-dependencies argument and hope it will just work. pip install wechatpy --no-dependencies (or whatever the package is called, I am not familiar with it) for example. This ignores the dependencies when installing. Maybe the requirements are outdated and this will let you proceed. For this you most likely want to satisfy the requests>=2.9.1 requirement so you should install python-social-auth normally and then try the other package without dependencies.
Look for older versions of the packages you are installing that have compatible requirements. Depending on the setup of your project this might not be possible to do because you need features of the later versions (or the old versions might be insecure).
You can try patching one of your requirements locally (download from the source, change the code to make it work with the conflicting requests version). And then import the local version of the packages. Remember to remove the requirement from your project's requirements.txt in this case to stop other people working on / using your project from running into the same issue, and include the local version as part of the project (track it on Git). Check the license of the packages you are modifying to see if you are allowed to modify and redistribute them. (Optional: Make a pull request on the packages' Github with your change(s) so other people can benefit from them)
Replace one or both of the packages by something else. They might just not be compatible or using a local, modified version might not be viable.
1 I get the warning msg when I pip install my Django project requirements 

wechat-sdk 0.6.4 has requirement requests==2.6.0, but you'll have
  requests 2.9.1 which is incompatible.

2 then follow the tips I uninstall requests and install proper version, but I get another warning

python-social-auth 0.2.21 has requirement requests>=2.9.1, but you'll
  have requests 2.6.0 which is incompatible.

So, I'm trapped in the endless loop
Can anyone give any advice?