https://source.cloud.google.com/results/invocations/ad826d9a-7e6b-43ac-bd17-3216b9f924f4/targets/%2F%2Ftest%2Fcore%2Fclient_channel:xds_bootstrap_test/tests

There are 3 test failures that happen fairly repeatably, but the most interesting one is XdsBootstrapTest.BadChannelCredsContents, which fails with the following error:

unknown file
SEH exception with code 0xc00000fd thrown in the test body.

I'll change the BUILD file to not run this test under Windows for now, but we should re-enable that once we figure out what's causing it.