code: function getFirstCommitOfFile(filePath) {
      let commits = execSilent(`git rev-list HEAD -- ${filePath}`);
  
      commits = splitCommandResultToLines(commits);
      return commits[commits.length - 1].trim();
  }
docs: Gets the first commit sha of the given file.
  @param {string} filePath The file path which should be checked.
  @returns {string} The commit sha.