Missing git command in pull request step-by-step guide

[zthompson47]

Hello,

I was following the pull request (PR) step-by-step guide from #103 and ran into an error with a git command. My PR has to do with a typo I found in the cpython documentation, and here are the steps to recreate the situation:

1. Begin at https://devguide.python.org/docquality/#helping-with-documentation-issues
2. Click "Quick Guide to Pull Requests" link
3. Click "got the source code" link
4. Follow instructions to fork, clone, and add upstream for cpython.git

(/tmp)$ git clone git@github.com:zthompson47/cpython.git
Cloning into 'cpython'...
remote: Enumerating objects: 757754, done.
remote: Total 757754 (delta 0), reused 0 (delta 0), pack-reused 757754
Receiving objects: 100% (757754/757754), 284.00 MiB | 2.60 MiB/s, done.
Resolving deltas: 100% (608403/608403), done.
Checking out files: 100% (4307/4307), done.
(/tmp)$ cd cpython 
(/tmp/cpython)$ git remote add upstream git@github.com:python/cpython.git
(/tmp/cpython)$ git remote -v
origin  git@github.com:zthompson47/cpython.git (fetch)
origin  git@github.com:zthompson47/cpython.git (push)
upstream        git@github.com:python/cpython.git (fetch)
upstream        git@github.com:python/cpython.git (push)

5. Go back to https://devguide.python.org/pullrequest/#step-by-step-guide
6. Try to "Create a new branch in your local clone"

(/tmp/cpython)$ git checkout -b new-local-branch upstream/master
fatal: 'upstream/master' is not a commit and a branch 'new-local-branch' cannot be created from it

I fixed the error by running git fetch upstream and repeating step six from above to create the branch. I'm no git expert, but I think the "Create a new branch in your local clone" could also just be git checkout -b <branch-name> as the upstream/master and local master branches should refer to the same commit at this point in the process.

I'm happy to submit a PR if warranted.

[methane]

Nice catch. Please add git fetch upstream before git checkout -b <branch-name> upstream/master.

but I think the "Create a new branch in your local clone" could also just be git checkout -b <branch-name> as the upstream/master and local master branches should refer to the same commit at this point in the process.

Please note that people may start from an existing local clone, instead of fresh git clone.
Their local master branch may be old. Or it may contain local changes by the user.
upstream/master is much safer than master.

[zthompson47]

Good point, and thanks for the quick feedback. I'll submit a PR later today.