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.
size = len(enum)
            copy_qwebcontext["%s_size" % varname] = size
        copy_qwebcontext["%s_all" % varname] = enum
        ru = []
        for index, (item, value) in enumerate(self._iterate(enum)):
            copy_qwebcontext.update({
                varname: item,
                '%s_value' % varname: value,
                '%s_index' % varname: index,
                '%s_first' % varname: index == 0,
            })
            if size is not None:
                copy_qwebcontext['%s_last' % varname] = index + 1 == size
            if index % 2:
                copy_qwebcontext.update({
                    '%s_parity' % varname: 'odd',
                    '%s_even' % varname: False,
                    '%s_odd' % varname: True,
                })
            else:
                copy_qwebcontext.update({
                    '%s_parity' % varname: 'even',
                    '%s_even' % varname: True,
                    '%s_odd' % varname: False,
                })
            ru.append(self.render_element(element, template_attributes, generated_attributes, copy_qwebcontext))
        for k in qwebcontext.keys():
            qwebcontext[k] = copy_qwebcontext[k]
        return "".join(ru)
    def render_tag_if(self, element, template_attributes, generated_attributes, qwebcontext):