Using standalone readability, version 0.6.0. Using the following minimal example:
<!DOCTYPE HTML">
<html>
<body>
<a href="https://www.debian.org/security/faq">https://www.debian.org/security/faq</a>
</body>
</html>
The string is parsed into a document using linkedom version 0.18.12. Inspecting the Node objects show the href as expected, without a slash.
Creating a new readability object and using the parse method however, generates an object with the href url having a newly added trailing slash. In this example, such a change leads to a 404 not found exception.