revision: drop explicit check for commit graph

revision: drop explicit check for commit graph

When filtering down revisions by paths we know to use bloom filters from
the commit graph, if we have any. The entry point for this is in
`check_maybe_different_in_bloom_filter()`, where we first verify that:

  - We do have a commit graph.

  - That the commit is contained therein by checking that we have a
    proper generation number.

  - And that the graph contains a bloom filter.

The first check is somewhat redundant though: if we don't have a commit
graph, then the second check would already tell us that we don't have a
generation number for the specific commit.

In theory this could be seen as a performance optimization to
short-circuit for scenarios where there is no commit graph. But in
practice this shouldn't matter: if there is no commit graph, then the
commit graph data slab would also be unpopulated and thus a lookup of
the commit should happen in constant time.

Drop the unnecessary check.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>