def run_cmd(cmd)
      raise "Unstubbed git command #{cmd}" if ENV['SCGITX_TEST'] == 'true'
      say "\n$ "
      say cmd.gsub("'", ''), :red
      raise "#{cmd} failed" unless system cmd
    end
def run_cmd(cmd)
      raise "Unstubbed git command #{cmd}" if ENV['SCGITX_TEST'] == 'true'
      say "\n$ "
      say cmd.gsub("'", ''), :red
      raise "#{cmd} failed" unless system cmd
    end
execute a shell command and raise an error if non-zero exit code is returned