On Tue, Apr 27 2021, Han-Wen Nienhuys via GitGitGadget wrote:

From: Han-Wen Nienhuys <redacted>

In reftable, there is no notion of a per-ref 'existence' of a reflog. Each
reflog entry has its own key, so it is not possible to distinguish between
{reflog doesn't exist,reflog exists but is empty}. This makes the logic
in log_ref_setup() (file refs/files-backend.c), which depends on the existence
of the reflog file infeasible.

Okey...

-test_expect_success '--orphan does not make reflog when core.logAllRefUpdates = false' '
+test_expect_success REFFILES '--orphan does not make reflog when core.logAllRefUpdates = false' '
 	git checkout main &&
 	git config core.logAllRefUpdates false &&
 	git checkout --orphan epsilon &&

But let's not simply skip the test, but positively test for the reftable
behavior here, or maybe that's planned for a later series.