differentiate reporting on incomplete and invalid

Author: nkrabben

bagit.py

@@ -855,7 +855,7 @@ def _validate_completeness(self):
             errors.append(e)
 
         if errors:
-            raise BagValidationError(_("Bag validation failed"), errors)
+            raise BagValidationError(_("Bag is incomplete"), errors)
 
     def _validate_entries(self, processes):
         """

test.py

@@ -219,7 +219,7 @@ def test_validation_completeness_error_details(self):
             got_exception = True
 
             exc_str = str(e)
-            self.assertIn("Bag validation failed: ", exc_str)
+            self.assertIn("Bag is incomplete: ", exc_str)
             self.assertIn(
                 "bag-info.txt exists in manifest but was not found on filesystem",
                 exc_str,