The isShardedTimeseries test helper is implemented as:

return FixtureHelpers.isSharded(coll) || FixtureHelpers.isSharded(getTimeseriesBucketsColl(coll))

It's possible that:

• "coll" is a sharded timeseries, in viewful format
• The first operand is evaluated. Since "coll" is in viewful format, it return false.
• "coll" gets upgraded to viewless timeseries
• The second operand is evaluated. Since "coll" is in viewless format, it return false.

So we would return false even though "coll" is sharded timeseries.