A PR found by searching for an existing head branch (find_open_pr_for_branch),
independent of any metadata the gh wrapper hook may or may not have recorded.
Every configured git remote’s GitHub repo slug (owner/repo) for
workspace, origin first (the common case, tried with no extra
requests) then any other remote in git remote order. Repos here
routinely carry a personal origin alongside an internal mirror remote —
PR detection must not assume a PR always lives against origin.
Returns an empty Vec if workspace isn’t a git repo or has no remotes.
Parse a git remote URL or bare slug into (owner, repo). Handles
“owner/repo”, “https://github.com/owner/repo(.git)”,
“ssh://[user@]host/owner/repo(.git)”, and scp-like SSH syntax
“[user@]host:owner/repo(.git)” — including a custom ssh config host
alias (e.g. git@github.com-work:owner/repo.git), which multi-remote
setups (a personal origin alongside an internal mirror reached via an
aliased SSH host) rely on and which a fixed github.com prefix can’t
recognize.