Following these directions exactly, I reviewed a Github pull request #42 from developer Foo, then made some changes and pushed them. This created a new PR (#43) with everything from #42 plus my local changes; note I have not yet opened the PR on Github, it's just pushed. If I want Foo to still make changes on her branch, which originally pushed #42, what is my course of action?
More generally, how can I pull in a PR and push changes such that Foo and I can both work on the same PR?
This SO question is related, but doesn't give a clear answer.