Typechecker tests failures

Hello, I was working on #9605, and found a number of failed tests: Unexpected failures: should_compile T7891 [exit code non-0] (hpc,optasm,optllvm) should_compile tc124 [exit code non-0] (hpc,optasm,optllvm) should_run T7861 [bad exit code] (normal,hpc,optasm,ghci,threaded1,threaded2,dyn,optllvm) They seem to be unrelated to my work, and they are skipped when "fast" is enabled. T7891 and tc124 fail with Core Lint errors. Looks like Phabricator uses "fast" way to validate revisions, so the failures were not noticed. Thanks, Yuras