[FIX] l10n_ar_account: proper compare document numbers in vendor bills

When creating vendor bills, it was considering this two numbers as different but actually are the same invoice number

* 01234-00000001
+ 1234-00000001

To avoid this we remove the zero to the left always if the pos number > 4.

closes odoo/odoo#41196

Signed-off-by: Josse Colpaert <jco@openerp.com>

addons/l10n_ar/models/l10n_latam_document_type.py

@@ -85,6 +85,8 @@ class L10nLatamDocumentType(models.Model):
                 failed = True
             elif len(number) > 8 or not number.isdigit():
                 failed = True
+            if len(pos) == 5 and pos[0] == '0':
+                pos = pos[1:]
             document_number = '{:>04s}-{:>08s}'.format(pos, number)
         if failed:
             raise UserError(msg % (document_number, self.name, _(