Derrick Stolee [off-list ref] writes:
My thought was that using a fixed name
(e.g. .git/objects/info/commit-graph) would block making the graph
incremental. Upon thinking again, this is not the case. That feature
could be designed with a fixed name for the small, frequently-updated
file and use .../info/graph-<hash>.graph names for the "base" graph
files.
I guess that is in line with the way how split-index folks did their
thing ;-)