When it's the first time a test is run, there'll not be previous results
to compare against. The script that calculates outliers was not prepared
for this situation. This commit just fixes that.
The new benchmark test for blobs fs backend was rebased from a merge
request in which it was written using the new interface for blobs
backend. After rebase, the test was not reverted to old interface, and
was just failing bad. This commit fixes it.