Return empty string if index-url not provided to AuthedUrlBuilder

[wssbck]

What are you trying to accomplish?

While AuthedUrlBuilder could be provided no index-url, it does not handle this case, making the following line cause an exception:

url.sub("://", "://#{basic_auth_details}@")

This can happen, for example, when tools like Dependabot for Azure DevOps do not provide index-url generally, as described in this issue:

tinglesoftware/dependabot-azure-devops#1167

Anything you want to highlight for special attention from reviewers?

Another approach would be to make Dependabot for Azure DevOps provide index-url for Python dependencies in credentials, however this would not fix the general issue of AuthedUrlBuilder not handling a nil index-url.

How will you know you've accomplished your goal?

tinglesoftware/dependabot-azure-devops#1167 will essentially become irrelevant.

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.

[kbukum1]

LGTM

[wssbck]

@kbukum1 thank you for reviewing. Do I need to update the branch for the PR to be merged?

[kbukum1]

@kbukum1 thank you for reviewing. Do I need to update the branch for the PR to be merged?

@wssbck, we will update the branch before merging. No action needed from your side right now.