Fetch tool can't fetch anything from GitHub.com

[mjbvz]

Every time an agent tries to fetch from GitHub.com, I get this error in the debug log:

Here is some relevant context from the web page https://github.com/microsoft/vscode-copilot-chat/compare/main...demiracl%3Avscode-copilot-chat%3Ademiracl/add-bb-policy:
Access to github.com is blocked by network domain policy (see `chat.agent.allowedNetworkDomains` and `chat.agent.deniedNetworkDomains` settings).

There are a few different bugs here:

1. Here is some relevant context from ... appears to be incorrect. We shouldn't use that wording in the context in this case

2. I don't have these settings configured so I'm unsure why this is being blocked

3. The user is shown this error message in the UI which is very confusing:

[dmitrivMS]

@mjbvz Do you have chat.agent.networkFilter or chat.agent.sandbox.enabled setting set to on?

[mjbvz]

chat.agent.networkFilter if off / unset

chat.agent.sandbox.enabled is on

[dmitrivMS]

Then the behavior is by design (sandbox). The error message being unclear for Fetch Tool is tracked by another issue already.
What we could do is add to the message about settings to check those two. @dileepyavan ?