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/test_converter/tests/test_html.py
def test_many2one(self):
        Sub = self.registry('test_converter.test_model.sub')
        id0 = self.Model.create(self.cr, self.uid, {
            'many2one': Sub.create(self.cr, self.uid, {'name': "Foo"})
        })
        id1 = self.Model.create(self.cr, self.uid, {
            'many2one': Sub.create(self.cr, self.uid, {'name': "Fo<b>o</b>"})
        })
        def converter(record):
            model = self.registry('ir.qweb.field.many2one')
            return e(model.record_to_html(self.cr, self.uid, 'many2one', record))
        value = converter(self.Model.browse(self.cr, self.uid, id0))
        self.assertEqual(value, "Foo")
        value = converter(self.Model.browse(self.cr, self.uid, id1))
        self.assertEqual(value, "Fo&lt;b&gt;o&lt;/b&gt;")
class TestBinaryExport(TestBasicExport):