The sourced stub returned a literal `[]` to --jq callers when a fixture
was missing, where the real API answers an empty list and the filter
yields nothing. last_issue_activity then sorted `[]` beside an ISO-8601
timestamp — and `[]` outsorts a timestamp in the C locale but not in a
UTF-8 one, so the sweep dated an issue by a stub artifact on the runner
and by created_at here.
The old code swallowed the resulting `date` failure and graded the claim
on a literal 0 anyway; #247's guards turn a failed read into a skip,
which is what made the lie visible. Adopt the arrival stub's shape.
Suite green under LC_ALL=C, C.UTF-8 and en_US.UTF-8.
Refs #247
f965e8404c