• I am on the latest Poetry version.
• I have searched the issues of this repo and believe that this is not a duplicate.
• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: Archlinux with Kernel Linux 5.4.11-arch1-1 & CentOS7 with Kernel Linux 3.10.0-1062.9.1.el7.x86_64
• Poetry version: 1.0.2
• Link of a Gist with the contents of your pyproject.toml file: pyproject.toml Gist

Issue

When trying to add statsmodels in dev version to the project on either of the two systems using

poetry add git+https://github.com/statsmodels/statsmodels.git -vvv

(and without -vvv), I get 'BinOp' object has no attribute 's' (full output with -vvv)
pip install git+https://github.com/statsmodels/statsmodels.git works fine though.