Wow!! Thank you so much for sharing this solution with us.
I also have been checking the Redmine requirements and it seems Git 2.14.1 is not supported, so that may be the reason why you are getting that error.
I was checking some solutions as downgrade the Git version to another one lower is not recommended since we updated that version due to a security issue in Git.
It would be also nice to fill an issue in Redmine to let the Redmine team about this
Again, thank you. This will help a lot to the community.