No space left on device errors

[htuch]

From https://oss-fuzz.com/v2/testcase-detail/5644730562510848:

[2018-08-23 21:05:44.628][22433][critical][assert] test/test_common/environment.cc:54] assert failure: ::mkdtemp(test_tmpdir) != nullptr. Details: Failed to create tmpdir /tmp/envoy_test_tmp.LBSV5i No space left on device

Thoughts on how we can be hitting this in ClusterFuzz? We started to run into issues like this after recently switching to using mkdtemp to attempt to give each fuzz test its own area of the filesystem, to reduce the chance of interactions between independent test cases.

[Dor1s]

Do you remove those dirs afterwards?

[htuch]

Yep, I had thought the artifacts would be small enough, but I guess they add up. Should be fixed by envoyproxy/envoy#4253.