blackbox: fix recording exit codes (issue3938) Previously the blackbox wrapped runcommand, but this failed to see the error codes that were created if an exception occurred. I moved that logging to now wrap _runcatch, so it can observe and log the actual error code (such as when a user ctrl+c's during a command). Updated the tests as well. Tested the change by running all the tests with the blackbox extension enabled and verifying nothing broke (aside from things that printed what extensions were enabeld). The progress tests are affected by calls to time.time() so they needed to be updated to pass.