It failed on Windows VS 2015:

 [2019/02/27 18:24:21.029] + ./src/libmongoc/Debug/test-libmongoc.exe -d -F test-results.json
 [2019/02/27 18:24:21.029] FAIL
 [2019/02/27 18:24:21.029] Assert Failure: 0 > 0
 [2019/02/27 18:24:21.029] C:\data\mci\4709715f64dc8f5af580425573d98743\mongoc\src\libmongoc\tests\test-mongoc-max-staleness.c:216  _test_last_write_date()

On this patch build.

The test does the following:

• sets heartbeatFrequencyMS to 500. That means the topology scanner should send ismaster's to each server if they were last updated >= 500ms ago.
• does server selection
• sleeps for 2 seconds
• does server selection again
• checks that the last_write_date has increased since the first server selection

But the error indicates the server description was not updated in the second server selection attempt.

It's unclear to me why this could have failed, unless the sleep really wasn't sleeping for 2 seconds, or if there's some other time dependant bug.