old_contents: """
  Use libraries from a virtualenv (by modifying sys.path) in production.
  Also add Zulip's root directory to sys.path
  """
  
  import os
  from os.path import dirname, abspath
  import sys
  
  BASE_DIR = dirname(dirname(dirname(abspath(__file__))))
  activate_this = os.path.join(
      BASE_DIR,
      "zulip-venv" if sys.version_info[0] == 2 else "zulip-py3-venv",
      "bin",
      "activate_this.py")
  if os.path.exists(activate_this):
      # this file will exist in production
      exec(open(activate_this).read(), {}, dict(__file__=activate_this))
  sys.path.append(BASE_DIR)
  
new_contents: """
  Use libraries from a virtualenv (by modifying sys.path) in production.
  Also add Zulip's root directory to sys.path
  """
  
  import os
  from os.path import dirname, abspath
  import sys
  
  BASE_DIR = dirname(dirname(dirname(abspath(__file__))))
  activate_this = os.path.join(
      BASE_DIR,
      "zulip-py3-venv",
      "bin",
      "activate_this.py")
  if os.path.exists(activate_this):
      # this file will exist in production
      exec(open(activate_this).read(), {}, dict(__file__=activate_this))
  sys.path.append(BASE_DIR)
  
subject: Drop Python 2 support.