do not show errors about already uploaded files

VERSION

@@ -1 +1 @@
-Version 2.00.0 (2012-06-05 17:38:13) dev
+Version 2.00.0 (2012-06-05 17:53:24) dev

gluon/sqlhtml.py

@@ -1130,6 +1130,23 @@ class SQLFORM(FORM):
             hideerror=hideerror,
             )
 
+        if not ret and self.record and self.errors:
+            ### if there are errors in update mode
+            # and some errors refers to an already uploaded file
+            # delete error if
+            # - user not trying to upload a new file
+            # - there is existing file and user is not trying to delete it
+            # this is because removing the file may not pass validation
+            for key in self.errors.keys():
+                if key in self.table \
+                        and self.table[key].type == 'upload' \
+                        and request_vars.get(key, None) in (None, '') \
+                        and self.record[key] \
+                        and not key + UploadWidget.ID_DELETE_SUFFIX in request_vars:
+                    del self.errors[key]
+            if not self.errors:
+                ret = True
+
         self.deleted = \
             request_vars.get(self.FIELDNAME_REQUEST_DELETE, False)