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
converter = self.get_converter('text')
        value = converter("This is my text-kai")
        self.assertEqual(value, "This is my text-kai")
        value = converter("""
            .  The current line (address) in the buffer.
            $  The last line in the buffer.
            n  The nth, line in the buffer where n is a number in the range [0,$].
            $  The last line in the buffer.
            -  The previous line. This is equivalent to -1 and may be repeated with cumulative effect.
            -n The nth previous line, where n is a non-negative number.
            +  The next line. This is equivalent to +1 and may be repeated with cumulative effect.
        """)
        self.assertEqual(value, """<br>
            .  The current line (address) in the buffer.<br>
            $  The last line in the buffer.<br>
            n  The nth, line in the buffer where n is a number in the range [0,$].<br>
            $  The last line in the buffer.<br>
            -  The previous line. This is equivalent to -1 and may be repeated with cumulative effect.<br>
            -n The nth previous line, where n is a non-negative number.<br>
            +  The next line. This is equivalent to +1 and may be repeated with cumulative effect.<br>
        """)
        value = converter("""
        fgdkls;hjas;lj <b>fdslkj</b> d;lasjfa lkdja <a href=http://spam.com>lfks</a>
        fldkjsfhs <i style="color: red"><a href="http://spamspam.com">fldskjh</a></i>
        """)
        self.assertEqual(value, """<br>
        fgdkls;hjas;lj &lt;b&gt;fdslkj&lt;/b&gt; d;lasjfa lkdja &lt;a href=http://spam.com&gt;lfks&lt;/a&gt;<br>
        fldkjsfhs &lt;i style=&quot;color: red&quot;&gt;&lt;a href=&quot;http://spamspam.com&quot;&gt;fldskjh&lt;/a&gt;&lt;/i&gt;<br>
        """)
class TestMany2OneExport(TestBasicExport):