Two shape fixes from the review of #92979, no behavior change:
- Read imap.capabilities directly instead of the getattr(...) or ()
fallback — a real imaplib.IMAP4 always sets the attribute in
_connect() (raising if the server sends no CAPABILITY), so the
default branch only existed for a MagicMock(spec=["xatom"]) that no
production path produces. Drop the test that pinned it.
- Trim tests to the invariant bar: the four mock tests duplicated what
test_email_imap_id_protocol.py proves on the wire (real imaplib, real
socket, command order), and the phase parametrize (startup vs poll)
exercised the same single _send_imap_id call site twice. Keep the
three id_mode cases through the poll path.
42 tests pass; mutation check: guard removed -> the absent-ID case
fails with the #39856 SELECT error, restored -> green.
66f1668850