Describe the bug

A clear and concise description of what the bug is. Include version by typing gh --version.

Steps to reproduce the behavior

git checkout -b 1234
echo foo > foo.txt && git commit foo.txt -m'foo'
gh pr create -t'foo' -b'bar'

Expected vs actual behavior

expected: it works
actual: the PR finder fails because it misinterprets a numerical Selector as a PR number instead of a branch name.