On Tue, May 24 2022, Johannes Schindelin via GitGitGadget wrote:

From: Johannes Schindelin <redacted>
[...]
Let's drop that local variable and introduce a new flag in the slot that
is used to indicate that even while the slot is no longer in use, it is
still reserved until further notice. It is the responsibility of
`run_active_slot()` to clear that flag once it is done with that slot.

Initial-patch-by: Junio C Hamano [off-list ref]

Don't you mean by me?
I.e. https://lore.kernel.org/git/patch-1.1-1cec367e805-20220126T212921Z-avarab@gmail.com/ (local)

This seems to be derived from that, or perhaps you just came up with
something similar independently. Junio then came up with the smaller
https://lore.kernel.org/git/xmqq8rv2nggn.fsf@gitster.g/ (local)