Checking out a PR from a fork by URL no longer works #10510

# Set up env vars
env REPO=${SCRIPT_NAME}-${RANDOM_STRING}

# Use gh as a credential helper
exec gh auth setup-git

# Create a repository with a file so it has a default branch
exec gh repo create ${ORG}/${REPO} --add-readme --private

# Defer upstream cleanup
defer gh repo delete --yes ${ORG}/${REPO}

# Create a fork
exec gh repo fork ${ORG}/${REPO} --org ${ORG} --fork-name ${REPO}-fork

# Defer fork cleanup
defer gh repo delete --yes ${ORG}/${REPO}-fork

# Clone both repos
exec gh repo clone ${ORG}/${REPO}
exec gh repo clone ${ORG}/${REPO}-fork

# Prepare a branch to PR in the fork itself
cd ${REPO}-fork
exec git checkout -b feature-branch
exec git commit --allow-empty -m 'Empty Commit'
exec git push -u origin feature-branch

# Create the PR inside the fork
exec gh repo set-default ${ORG}/${REPO}-fork
exec gh pr create --title 'Feature Title' --body 'Feature Body'
stdout2env PR_URL

# Checkout the PR by full URL in the upstream repo
cd ${WORK}/${REPO}
exec gh pr checkout ${PR_URL}
stderr 'Switched to branch ''feature-branch'''

        [git -c credential.helper= -c credential.helper=!"/var/folders/45/sdnm1hp10nj1s9q57dp3bc5h0000gn/T/testscript-main1265888467/bin/gh" auth git-credential fetch origin +refs/heads/feature-branch:refs/remotes/origin/feature-branch --no-tags]
        fatal: couldn't find remote ref refs/heads/feature-branch
        failed to run git: exit status 128