[FIX] base_vat: support Irish Tax numbers introduced in 2013

This is a temporary fix until upstream is fixed.
References: 
- http://en.wikipedia.org/wiki/Personal_Public_Service_Number
- https://www.welfare.ie/en/Pages/Extension-of-the-Personal-Public-Service-Number-Range.aspx

bzr revid: odo@openerp.com-20140213141246-t56sx1t8x4riey4w

addons/base_vat/base_vat.py

@@ -54,7 +54,7 @@ _ref_vat = {
     'gr': 'GR12345670',
     'hu': 'HU12345676',
     'hr': 'HR01234567896', # Croatia, contributed by Milan Tribuson 
-    'ie': 'IE1234567T',
+    'ie': 'IE1234567FA',
     'it': 'IT12345670017',
     'lt': 'LT123456715',
     'lu': 'LU12345613',
@@ -190,6 +190,34 @@ class res_partner(osv.osv):
             return check == int(num[8])
         return False
 
+    def _ie_check_char(self, vat):
+        vat = vat.zfill(8)
+        extra = 0
+        if vat[7] not in ' W':
+            if vat[7].isalpha():
+                extra = 9 * (ord(vat[7]) - 64)
+            else:
+                # invalid
+                return -1
+        checksum = extra + sum((8-i) * int(x) for i, x in enumerate(vat[:7]))
+        return 'WABCDEFGHIJKLMNOPQRSTUV'[checksum % 23]
+
+    def check_vat_ie(self, vat):
+        """ Temporary Ireland VAT validation to support the new format
+        introduced in January 2013 in Ireland, until upstream is fixed.
+        TODO: remove when fixed upstream"""
+        if len(vat) not in (8, 9) or not vat[2:7].isdigit():
+            return False
+        if len(vat) == 8:
+            # Normalize pre-2013 numbers: final space or 'W' not significant
+            vat += ' '
+        if vat[:7].isdigit():
+            return vat[7] == self._ie_check_char(vat[:7] + vat[8])
+        elif vat[1] in (string.ascii_uppercase + '+*'):
+            # Deprecated format
+            # See http://www.revenue.ie/en/online/third-party-reporting/reporting-payment-details/faqs.html#section3
+            return vat[7] == self._ie_check_char(vat[2:7] + vat[0] + vat[8])
+        return False
 
     # Mexican VAT verification, contributed by <moylop260@hotmail.com>
     # and Panos Christeas <p_christ@hol.gr>