QueryTester's --drop --load optimization looks at the collection definition line from the test file and decides whether a collection is stale based on that string. This can create problems when the directory structure looks like

If both agg.test files include their respective agg.coll files, the relative paths would look identical, causing both to have the line agg.coll as collName. If mongotest is run with both test files, e.g. -t dir1/agg.test -t dir2/agg.test, then the optimization will think that it can skip the second agg.coll load, even though the collection definitions are actually different.