Fix raw_io input placeholders not using unicode.

recipe_modules/raw_io/api.py

 # Copyright 2014 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.
 
 from recipe_engine import recipe_api
 from recipe_engine import util as recipe_util
 
 import os
 import shutil
 import tempfile
@@ skipping 12 matching lines @@
     return self._backing_file
 
   def render(self, test):
     assert not self._backing_file, 'Placeholder can be used only once'
     if test.enabled:
       # cheat and pretend like we're going to pass the data on the
       # cmdline for test expectation purposes.
       self._backing_file = self.data
     else:  # pragma: no cover
       input_fd, self._backing_file = tempfile.mkstemp(suffix=self.suffix)
-      os.write(input_fd, self.data)
+      os.write(input_fd, self.data.encode('utf-8'))
       os.close(input_fd)
     return [self._backing_file]
 
   def cleanup(self, test_enabled):
     assert self._backing_file is not None
     exists = os.path.exists(self._backing_file)
     if not test_enabled and exists:  # pragma: no cover
       os.unlink(self._backing_file)
     self._backing_file = None
 
@@ skipping 110 matching lines @@
     """Returns a directory Placeholder for use as a step argument.
 
     If 'leak_to' is None, the placeholder is backed by a temporary dir with
     a suffix 'suffix'. The dir is deleted when the step finishes.
 
     If 'leak_to' is not None, then it should be a Path and placeholder
     redirects IO to a dir at that path. Once step finishes, the dir is
     NOT deleted (i.e. it's 'leaking'). 'suffix' is ignored in that case.
     """
     return OutputDataDirPlaceholder(suffix, leak_to, name=name)