Automatically add upstream during PR creation

[burkeholland]

When creating a new PR, we should automatically create an upstream for the user if they do not already have one defined. Proposed workflow....

1. User creates new PR
2. Extension prompts them for origin or "parent"
3. User selects "parent"
4. Extension prompts with: "Submitting a PR requires that the parent repo be added as an "upstream" remote. Would you like to add it as the upstream now?" (Yes / Cancel - kills the whole workflow)
5. User selects "Yes"
6. Parent is added as upstream
7. PR is created

Linking https://github.com/microsoft/vssaas-planning/issues/2176

[burkeholland]

Come to think of it, we don't need to ask them - we can just do it. They've said they want to create a PR, you have to have an upstream to do that, congratulations on your new upstream.

[bamurtaugh]

Hey @RMacfarlane, just to clarify - how does this feature look in action?

When I create a PR on https://github.com/chrisdias/gh-static-e2e, which is a fork of https://github.com/fiveisprime/gh-static-e2e, should fiveisprime/gh-static-e2e automatically be added as an upstream and listed as an option in the dropdowns (that's what I anticipated, but I'm only seeing chrisdias/gh-static-e2e, so perhaps this is different than my understanding):

v2021.3.22143 of GHPRI Nightly

Version: 1.55.0-insider
Commit: 892a1083cb2b9b3987ff7edc85376b5d9764433d
Date: 2021-03-16T05:11:52.701Z
Browser: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.82 Safari/537.36

[RMacfarlane]

Yeah, that's correct, there should be an upstream added in this case. Talked offline, Brigit has been able to verify last week, was seeing weird behavior before where the stable version of the extension seemed to still be active.

To verify:

• Use nightly version of the extension
• Fork a repo
• Open the fork in VS Code
• After the extension initializes, there should be both an origin and upstream when running git remote -v