Previously, running the tests with RUST_LOG=none would fail, because the
env logger would set its filter level to reject all log messages, and
incrementing a counter only happens if the global logger has at least
the specified log level. Having the tests behave differently when
RUST_LOG is set is surprising, they should be self-contained.
Nix' buildRustPackage sets RUST_LOG="" to make the build logs less
verbose. I have trouble packaging Solana for Nix because of this, and I
believe making the tests independent of the environment is a good
solution for this.
3f92abedd5