def build_start_time
      @build_start_time ||= begin
                              if ENV["BUILD_TIMESTAMP"]
                                begin
                                  Time.strptime(ENV["BUILD_TIMESTAMP"], "%Y-%m-%d_%H-%M-%S")
                                rescue ArgumentError
                                  error_message =  "BUILD_TIMESTAMP environment variable "
                                  error_message << "should be in YYYY-MM-DD_hh-mm-ss "
                                  error_message << "format."
                                  raise ArgumentError, error_message
                                end
                              elsif ENV["BUILD_ID"]
                                begin
                                  Time.strptime(ENV["BUILD_ID"], "%Y-%m-%d_%H-%M-%S")
                                rescue ArgumentError
                                  error_message =  "BUILD_ID environment variable "
                                  error_message << "should be in YYYY-MM-DD_hh-mm-ss "
                                  error_message << "format."
                                  raise ArgumentError, error_message
                                end
                              else
                                Time.now.utc
                              end
                            end.strftime(TIMESTAMP_FORMAT)
    end
def build_start_time
      @build_start_time ||= begin
                              if ENV["BUILD_TIMESTAMP"]
                                begin
                                  Time.strptime(ENV["BUILD_TIMESTAMP"], "%Y-%m-%d_%H-%M-%S")
                                rescue ArgumentError
                                  error_message =  "BUILD_TIMESTAMP environment variable "
                                  error_message << "should be in YYYY-MM-DD_hh-mm-ss "
                                  error_message << "format."
                                  raise ArgumentError, error_message
                                end
                              elsif ENV["BUILD_ID"]
                                begin
                                  Time.strptime(ENV["BUILD_ID"], "%Y-%m-%d_%H-%M-%S")
                                rescue ArgumentError
                                  error_message =  "BUILD_ID environment variable "
                                  error_message << "should be in YYYY-MM-DD_hh-mm-ss "
                                  error_message << "format."
                                  raise ArgumentError, error_message
                                end
                              else
                                Time.now.utc
                              end
                            end.strftime(TIMESTAMP_FORMAT)
    end
We'll attempt to retrieve the timestamp from the Jenkin's set BUILD_TIMESTAMP
 or fall back to BUILD_ID environment variable. This will ensure platform specfic
 packages for the same build will share the same timestamp.