TestIOFencing fails intermittently due to compaction kicking in too soon

Here is one example: https://builds.apache.org/job/HBase-TRUNK/lastCompletedBuild/testReport/org.apache.hadoop.hbase/TestIOFencing/testFencingAroundCompactionAfterWALSync/

It failed on this assertion:

      assertTrue(compactingRegion.countStoreFiles() > 1);

I searched for "Blocking compactions" but didn't find it in the test output.
I think the compaction kicked in too soon, resulting in store file count being 1.