swarming: Add server-side implementation for supplemental bot_config

appengine/swarming/swarming_bot/bot_code/bot_main.py

 # Copyright 2013 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 """Swarming bot main process.
 
 This is the program that communicates with the Swarming server, ensures the code
 is always up to date and executes a child process to run tasks and upload
 results back.
 
@@ skipping 122 matching lines @@
     from config import bot_config as _BOT_CONFIG
   return _BOT_CONFIG
 
 
 def _register_extra_bot_config(content):
   """Registers the server injected extra bot_config.py.
 
   This file is called implicitly by _call_hook() and _call_hook_safe().
   """
   global _EXTRA_BOT_CONFIG
+  if isinstance(content, unicode):
+    # compile will throw if there's a '# coding: utf-8' line and the string is
+    # in unicode. <3 python.
+    content = content.encode('utf-8')
   try:
     compiled = compile(content, 'bot_config.py', 'exec')
     _EXTRA_BOT_CONFIG  = types.ModuleType('bot_config')
     exec(compiled, _EXTRA_BOT_CONFIG.__dict__)
   except (SyntaxError, TypeError) as e:
     _set_quarantined('handshake returned invalid bot_config: %s' % e)
 
 
 def _log_call(name=None):
   def gen(fn):
@@ skipping 962 matching lines @@
   error = None
   if len(args) != 0:
     error = 'Unexpected arguments: %s' % args
   try:
     return _run_bot(error)
   finally:
     _call_hook_safe(
         True, bot.Bot(None, None, None, None, base_dir, None),
         'on_bot_shutdown')
     logging.info('main() returning')