functional_tests: fix piecemeal export in cold_signing, part 2

Do not mark output import as done if exception is thrown for output being past last imported output.

Author: jeffro256

tests/functional_tests/cold_signing.py

@@ -124,6 +124,8 @@ def export_import(self, piecemeal_output_export):
                     # new outputs first
                     if 'Imported outputs omit more outputs that we know of' not in str(e):
                         raise
+                    else:
+                        continue
                 for i in range(start, start + count):
                     if i < len(done):
                         done[i] = True