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
html_url_format = '%s'
    def __init__(self, bundle, inline=None, url=None):
        self.id = str(uuid.uuid4())
        self.bundle = bundle
        self.inline = inline
        self.url = url
        self.html_url_args = url
        self.cr = bundle.cr
        self.uid = bundle.uid
        self.registry = bundle.registry
        self.context = bundle.context
        self._content = None
        self._filename = None
        self._ir_attach = None
        name = '<inline asset>' if inline else url
        self.name = "%s defined in bundle '%s'" % (name, bundle.xmlid)
        if not inline and not url:
            raise Exception("An asset should either be inlined or url linked")
    @property
    def html_url(self):