TST: skip testing on windows for specific formatting which sometimes hang
xref #14626
this is the reason *sometimes* appeveyor doesn't complete. Can we just skip the test when the result of `datetime.now()` has zero's at the end:

```
now = datetime.now()
if str(now).endswith("000"):
    nose.skipTest()
index = Index([now])
```

then we don't have the confusing spurious test failures (what the convoluted while function tried to solve) can't skip the entire test, but I put a conditional in there.