Git push with options - ci.variable is not recognized via gitpython

We are using gitpython to manage the local git repository. We are also using git push with options to pass on CI build variables during PUSH. However, the following is not working:

import git
repo = git.Repo ('/path/to/repo')
repo.remotes.origin.push("-o ci.variable='env_1=env_value_1'")

This might not be a bug in our code but with gitpython because when we use

git push -o ci.variable='env_1=env_value_1'

then, it works fine.

Another point to be noted is that when using

repo.remotes.origin.push("-o ci.variable='env_1=env_value_1'")

the build is not triggerred at all. However, when we replace the `o` with `-push-option` the build is triggered.