[PATCH v3 1/4] alloc: introduce parsed_commits_count

[Abhishek Kumar <abhishekkumar8222@gmail.com>]

Commit slab relies on uniqueness of commit->index to access data. As
submodules are repositories on their own, alloc_commit_index() (which
depends on repository->parsed_objects->commit_count) no longer
returns unique values.

This would break tests once we move `generation` and `graph_pos` into a
commit slab, as commits of supermodule and submodule can have the same
index but must have different graph positions.

Let's introduce a counter variable, `parsed_commits_count` to keep track
of parsed commits so far.


Signed-off-by: Abhishek Kumar <abhishekkumar8222@gmail.com>
---

CI Build for the failing tests:
https://travis-ci.com/github/abhishekkumar2718/git/jobs/345413840

 alloc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/alloc.c b/alloc.c
index 1c64c4dd16..29f0e3aa80 100644
--- a/alloc.c
+++ b/alloc.c
@@ -101,7 +101,9 @@ void *alloc_object_node(struct repository *r)
 
 static unsigned int alloc_commit_index(struct repository *r)
 {
-	return r->parsed_objects->commit_count++;
+	static unsigned int parsed_commits_count = 0;
+	r->parsed_objects->commit_count++;
+	return parsed_commits_count++;
 }
 
 void init_commit_node(struct repository *r, struct commit *c)
-- 
2.27.0