resolveRef accepts N, #N, [HOST/]OWNER/REPO#N and issue, pull request or run
URLs; a URL or qualified number selects its repository for the invocation and
must agree with --repo. resolveRefs does the same for several references.
pullSelector also accepts a head branch or OWNER:BRANCH and, without an
argument, finds the pull request of the checked-out branch: the one pr
checkout recorded in branch.<name>.tea-pr, else the open pull request whose
head is the branch's upstream in the upstream remote's repository, else one
whose head has the local branch's name, else N of a pr/N branch. This lets pr
commands find the pull request of a branch pr checkout created.
target.expandMe resolves @me in user-valued flags to the login tea acts as,
and git.CurrentBranchConfig reads the branch configuration involved.
Signed-off-by: bircni <bircni@icloud.com>