Re: [PATCH 0/3] Fix use of 'cache_bottom' in sparse index

"Victoria Dye via GitGitGadget" [off-list ref] writes:

...
To fix this, the 'cache_bottom' advancement is reinstated in
'mark_ce_used(...)', and instead it is disabled in 'unpack_callback(...)' if
the tree in question is a sparse directory. This corrects both the
non-"cache diff" cases and the 'unpack_index_entry(...)' cases while
preventing the double-advancement 17a1bb570b originally intended to avoid
(patch [2/3]).

;-).