Bigtable system test has a "race condition" if run simultaneously on same project

[dhermes]

Two builds (1682 and 1683) were happening simultaneously and this caused a Bigtable system test check to fail in the second build (1683)

>       self.assertEqual(len(instances), len(EXISTING_INSTANCES) + 1)
E       AssertionError: 2 != 3

This is because EXISTING_INSTANCES is set at module setup time while the test case is run later.

I'm not sure what a realistic fix should be?

[lukesneeringer]

I think the correct answer to this is "do nothing". If it happens more frequently, we can address it.

[dhermes]

I agree @lukesneeringer, though I've seen ~5 such failures in the last two days