message: Fix bug where `show` would fail if reading from stdin.
diff: @@ -8,6 +8,7 @@ import argparse
  import atexit
  import base64
  import hashlib
  +import os
  import os.path
  import sys
  import termios
  @@ -70,6 +71,8 @@ def ShowStdin(mimeType=None, charset=None, filenameMeta=None, download=False):
  def TurnOffEcho():
  # Turn off echo on the tty.
  fd = sys.stdin.fileno()
  + if not os.isatty(fd):
  + return
  old_settings = termios.tcgetattr(fd)
  new_settings = termios.tcgetattr(fd)
  new_settings[3] = new_settings[3] & ~termios.ECHO # lflags
  