Impacted versions: ODOO 10

Problem.
If i print a invoice with a negative amount, the pdf shows a vertical bar instead of a minus symbol.
![image](https://cloud.githubusercontent.com/assets/28800797/26237253/b07fadb0-3c74-11e7-86c2-c8688d82b5a5.png)

I have tried to install a new pdf reader, but with no result.
openerp/addons/base/ir/ir_qweb.py
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, xmlid, cr=None, uid=None, context=None, registry=None, max_css_rules=MAX_CSS_RULES):
        self.xmlid = xmlid
        self.cr = request.cr if cr is None else cr
        self.uid = request.uid if uid is None else uid
        self.context = request.context if context is None else context
        self.registry = request.registry if registry is None else registry
        self.max_css_rules = max_css_rules
        self.javascripts = []
        self.stylesheets = []
        self.css_errors = []
        self.remains = []
        self._checksum = None
        context = self.context.copy()
        context['inherit_branding'] = False
        context['inherit_branding_auto'] = False
        context['rendering_bundle'] = True
        self.html = self.registry['ir.ui.view'].render(self.cr, self.uid, xmlid, context=context)
        self.parse()
    def parse(self):