Update the version of golangci-lint we use in our docker image,
and update the version of the docker image we use in our tests.
Fix a couple places where we were violating lints (ineffective assign
and calling `t.Fatal` from outside the main test goroutine), and add
one lint (using math/rand) to the ignore list.
Fixes#5710
If the FAKECLOCK environment variable is set, and the build was in a
test environment, cmd.Clock will return a FakeClock with the time set to
the content of the environment variable.
The choice of the UnixDate format was because `date -d` is a common
choice for shell scripts.
Aaron Gable
Jacob Hoffman-Andrews
Kane York