patches: Fix a bug on sqlvar type="nb".

product/ERP5Type/patches/sqlvar.py

@@ -153,14 +153,10 @@ else: # For easy diff with original (ZSQLMethods 3.14)
                     ('.%06u' % (v.micros() % 1000000))[:1+n] if n else '')
             except Exception:
                 t = 'datetime'
-
-        elif t=='nb' and not v:
-            t = 'empty string'
-
         else:
             if not isinstance(v, (str, StringTypes)):
                 v = str(v)
-            if t == 'nb':
+            if not v and t == 'nb':
                 if 'optional' in args and args['optional']:
                     return 'null'
                 else: