According document of 'What’s New In Python 3.7', 'async' are reserved keywords now.

Code in line 105 of 'odoo/addons/base/ir/ir_qweb/assetsbundle.py' 
`def to_html(self, sep=None, css=True, js=True, debug=False, async=False, url_for=(lambda url: url)):`
will throw SyntaxError out if we launch odoo with this update python.
from psycopg2 import OperationalError
from types import CodeType
import logging
import sys
import werkzeug
from . import pycompat
from .misc import ustr
from . import pycompat
import odoo
unsafe_eval = eval
__all__ = ['test_expr', 'safe_eval', 'const_eval']
_ALLOWED_MODULES = ['_strptime', 'math', 'time']
_UNSAFE_ATTRIBUTES = ['f_builtins', 'f_globals', 'f_locals', 'gi_frame',
                      'co_code', 'func_globals']
_POSSIBLE_OPCODES_P3 = [
    
    'WITH_CLEANUP_START', 'WITH_CLEANUP_FINISH',
    
    'FORMAT_VALUE', 'BUILD_STRING',
    
    'UNPACK_EX',
    
    'BUILD_LIST_UNPACK', 'BUILD_TUPLE_UNPACK', 'BUILD_SET_UNPACK', 'BUILD_MAP_UNPACK',
    
    'BUILD_TUPLE_UNPACK_WITH_CALL', 'BUILD_MAP_UNPACK_WITH_CALL',
    
    'GET_YIELD_FROM_ITER',
    
    'BINARY_MATRIX_MULTIPLY', 'INPLACE_MATRIX_MULTIPLY',
]