Re: [PATCH 2/3] commit: write commit-graph with bloom filters

Derrick Stolee [off-list ref] writes:

If we keep this simple, or extract the process to a
"write_commit_graph_for_tests()" macro inside builtin.h, then we could
insert a commit-graph write in more places.

As long as the check necessary is cheap enough to realize that we
are in production mode, we should be able to keep the run-time
overhead to the minimum.  Sprinkling such a call all over the place,
however, might add to the overhead of reading code, though.

However, I think there is value in testing the "not every commit is
included in the commit-graph" case, which our current setup does quite
nicely.

Yeah, that is also a good point.

The one exception is that 'git merge' could benefit from this
snippet, so we cap off the commit-graph whenever a test script
"constructs" a repository to match a data shape.

Sounds good.

The problem here is that if GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS=1 and
someone runs "git commit-graph write --no-changed-paths" then the
negation of that option is ignored. But this is a GIT_TEST_* variable,
and any test that requires that check could disable the enviroment
variable first.

Yeah, that sounds good.