Linus Torvalds [off-list ref] writes:

When you say that v2.6.38 is good, that means that everything that can
be reached from 2.6.38 is good.

NOT AT ALL the same thing as "git bisect requires v2.6.38" would be.

The "requires v2.6.38" would basically say that anything that doesn't
contain v2.6.38 is "off-limits". It's fine to call them "good", but
that's not the same thing as "git bisect good v2.6.38".

Why?

Think about it. It's the "reachable from v2.6.38" vs "cannot reach
v2.6.38" difference. That's a HUGE difference.

Could you please clarify "off-limits"?

Do you mean "anything before v2.6.38 did not even have this feature, so
the result of testing a version in that range does not give us any
information"?  The feature didn't even exist, so a bug can never trigger,
and seeing "good" from such a version does not mean everything reachable
from it is good?  Upon seeing "bad" result from a version before v2.6.38,
what can we conclude?  The breakage cannot possibly come from the feature
that is being checked, so the procedure to check itself is busted?