Function set_GIT_COMMIT 

pub fn set_GIT_COMMIT() -> Result<(), String>

Sets the GIT_COMMIT env variable.

Call this from build.rs. Use env! in your main.rs to use the variable.

Example value: "a5547bfb1edb9712588f0f85d3e2c8ba618ac51f"

Related: rerun_if_git_commit_or_branch_changed

Errors

Returns an error if it fails to execute the git command.