testlog: capture through a single global subscriber that routes each
event to a thread-local sink and returns Interest::sometimes, so
tracing's global per-callsite interest cache can never short-circuit a
live capture when another thread rebuilds it. The old scoped
with_default lost events at random in the full suite (an empty capture
failed the log-accounting assertions ~1 run in 15).
labels: capture the escaping test through testlog instead of installing
its own process-wide subscriber, which hard-cached every foreign
callsite "off" and poisoned the captures above.
dirimage: name scratch directories from a process-monotonic counter
rather than SystemTime, which resolves to only a microsecond — two of
the parallel tests sharing a tag drew the same value, collided on one
directory, and the first to finish removed it out from under the
other's reads.
Matthew Jackson
341e079e1e