Update an incorrectly implemented method

[munahaf]

In file: label.py, class: Label, there is a special method __lt__ that raises a NotImplementedError. If a special method supporting a binary operation is not implemented it should return NotImplemented. On the other hand, NotImplementedError should be raised from abstract methods inside user defined base classes to indicate that derived classes should override those methods. I suggested that the special method __lt__ should return NotImplemented instead of raising an exception.

Sponsorship and Support:

This work is done by the security researchers from OpenRefactory and is supported by the Open Source Security Foundation (OpenSSF): Project Alpha-Omega. Alpha-Omega is a project partnering with open source software project maintainers to systematically find new, as-yet-undiscovered vulnerabilities in open source code - and get them fixed – to improve global software supply chain security.

The bug is found by running the Intelligent Code Repair (iCR) tool by OpenRefactory and then manually triaging the results.