Custom github link in config.toml

Hi all! My theme has the github URL for the site defined in the config.toml ( Each branch publishes to a different URL and I want the github URL to point to the correct branch. I have code that will dissect the branch from the URL ( but it doesn’t seem to me that I can just put this code in the config.toml.

Any ideas how to get the logic into the github URL specified in the config.toml?

In the end, I changed the name of the branch in the github link in the config.toml to “branch” and added this command before the build to replace it with the real branch name:
sed -i s/branch/${CIRCLE_BRANCH}/g config.toml

Once I found in a search that I could remove the quotes from the replace statement so that CIRCLE_BRANCH would resolve, worked like a charm!