stats test on Windows is now failing repeatably?

I just looked over the buildfarm results and was struck by the
observation that the stats regression test, which lately had been
failing once-in-a-while on Windows and never anywhere else, has a
batting average of 0-for-10-or-so over the past 24 hours on the Windows
buildfarm machines.  I still have no idea what the real problem is there
--- but since it suddenly seems to have gotten very repeatable, I trust
someone with a Windows box and a debugger will get after it before the
source code drifts again.

[ urk ... must ... resist ... temptation ... failing ... AUTOVACUUM? ]
        regards, tom lane