Race condition in cdr package test

[benileo]

WARNING: DATA RACE
Write by goroutine 24:
  sync.raceWrite()
      /tmp/workdir/go/src/sync/race.go:41 +0x2e
  sync.(*WaitGroup).Wait()
      /tmp/workdir/go/src/sync/waitgroup.go:124 +0xf9
  net/http/httptest.(*Server).Close()
      /tmp/workdir/go/src/net/http/httptest/server.go:168 +0x80
  github.com/letsencrypt/boulder/cdr.TestLookupCAA()
      /go/src/github.com/letsencrypt/boulder/cdr/resolver_test.go:101 +0xe00

[rolandshoemaker]

Was this run on current master or a version pre- 6264706, which I believe fixed this race.

[benileo]

I'm fairly certain it was post-6264706 as my first commit on that branch was 999383f.

Here is a link to the build https://travis-ci.org/letsencrypt/boulder/jobs/140300139

[rolandshoemaker]

Actually looking at it a bit closer this is just another case of golang/go#12262 which will be fixed by #1514.

[rolandshoemaker]

(dropping from sprint since #1514 is not likely to be done by next week)

[jsha]

We've worked around the Server.Close issue in other tests by simply not closing the test server. Can we do that here? Flaky tests are bad.