appender: test `logs_dropped_if_lossy` is flaky

[hawkw]

Bug Report

Crates

tracing-appender

Description

The test non_blocking::test::logs_dropped_if_lossy fails spuriously on CI with some frequency.

We a better understanding of what's going on here and determine if it's a bug in the implementation or just a test issue.

See #737 and #748 (comment).