oss-fuzz/commit-graph: set up hash algorithm

Our fuzzing setups don't work in a proper repository, but only use the
in-memory configured `the_repository`. Consequently, we never go through
the full repository setup procedures and thus do not set up the hash
algo used by the repository.

The commit-graph fuzzer does rely on a properly initialized hash algo
though. Initialize it explicitly.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

oss-fuzz/fuzz-commit-graph.c

@@ -19,6 +19,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
 	 * touching the disk to keep the individual fuzz-test cases as fast as
 	 * possible.
 	 */
+	repo_set_hash_algo(the_repository, GIT_HASH_SHA1);
 	the_repository->settings.commit_graph_generation_version = 2;
 	the_repository->settings.commit_graph_read_changed_paths = 1;
 	g = parse_commit_graph(&the_repository->settings, (void *)data, size);