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.
r')(?:[\000-\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/'
        r'))*((?:/(?![\r\n/*])[^/\\\[\r\n]*(?:(?:\\[^\r\n]|(?:\[[^\\\]\r\n]*'
        r'(?:\\[^\r\n][^\\\]\r\n]*)*\]))[^/\\\[\r\n]*)*/)[^\047"/\000-\040]*'
        r'))|(?:(?<=[\000-#%-,./:-@\[-^`{-~-]return)(?:[\000-\011\013\014\01'
        r'6-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/))*((?:/(?![\r\n/*])[^/'
        r'\\\[\r\n]*(?:(?:\\[^\r\n]|(?:\[[^\\\]\r\n]*(?:\\[^\r\n][^\\\]\r\n]'
        r'*)*\]))[^/\\\[\r\n]*)*/)[^\047"/\000-\040]*))|(?<=[^\000-!#%&(*,./'
        r':-@\[\\^`{|~])(?:[\000-\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:[^/'
        r'*][^*]*\*+)*/))*(?:((?:(?://[^\r\n]*)?[\r\n]))(?:[\000-\011\013\01'
        r'4\016-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/))*)+(?=[^\000-\040"#'
        r'%-\047)*,./:-@\\-^`|-~])|(?<=[^\000-#%-,./:-@\[-^`{-~-])((?:[\000-'
        r'\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/)))+(?=[^'
        r'\000-#%-,./:-@\[-^`{-~-])|(?<=\+)((?:[\000-\011\013\014\016-\040]|'
        r'(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/)))+(?=\+)|(?<=-)((?:[\000-\011\0'
        r'13\014\016-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/)))+(?=-)|(?:[\0'
        r'00-\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/))+|(?:'
        r'(?:(?://[^\r\n]*)?[\r\n])(?:[\000-\011\013\014\016-\040]|(?:/\*[^*'
        r']*\*+(?:[^/*][^*]*\*+)*/))*)+', subber, '\n%s\n' % script
    ).strip()
    return result
class AssetError(Exception):
    pass
class AssetNotFound(AssetError):
    pass
class AssetsBundle(object):
    rx_css_import = re.compile("(@import[^;{]+;?)", re.M)
    rx_preprocess_imports = re.compile("""(@import\s?['"]([^'"]+)['"](;?))""")
    rx_css_split = re.compile("\/\*\! ([a-f0-9-]+) \*\/")
    
    def __init__(self, name, files, remains=None, env=None):