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
def raise_qweb_exception(etype=None, **kw):
    if etype is None:
        etype = QWebException
    orig_type, original, tb = sys.exc_info()
    try:
        raise etype, original, tb
    except etype, e:
        for k, v in kw.items():
            e.qweb[k] = v
        
        e.qweb['cause'] = original
        raise
def _build_attribute(name, value):
    value = escape(value)
    if isinstance(name, unicode): name = name.encode('utf-8')
    if isinstance(value, unicode): value = value.encode('utf-8')
    return ' %s="%s"' % (name, value)
class FileSystemLoader(object):
    def __init__(self, path):
        
        self.path = path
        self.doc = etree.parse(path).getroot()
    def __iter__(self):
        for node in self.doc:
            name = node.get('t-name')
            if name:
                yield name
    def __call__(self, name):