The cycle scenarios all pass with the old grep-based detection too;
the bug the `case`-based detection actually fixes is resolved names interpolated into the grep pattern as regexes,
where resolving axb -> a.b falsely reported ∞ because the pattern `a.b` matches the seen name `axb`.
Pin both directions: the fixed false positive, and a genuine cycle through a metachar name.
Also correct the space-name scenario comment
(the old anchored grep passed that scenario; only token-delimited seen-storage would not),
and register every new fixture name in the suite teardown,
so a mid-test failure can not leak aliases into later tests.
Jordan Harband
ebada63259