v15.4.0
Use [Git Environment Variables](https://git-scm.com/book/en/v2/Git-Internals-Environment-Variables#Committing). Set default values if environement variables are not set.
Use [Git Environment Variables](https://git-scm.com/book/en/v2/Git-Internals-Environment-Variables#Committing). Set default values if environement variables are not set.