object-file: lift ODB reprepare out of packfile flush

When flushing a packfile via `flush_packfile_transaction()`,
`odb_reprepare()` is invoked so the written packfile becomes visible in
the current process. In a subsequent commit, flushing the packfile is
performed earlier when committing a "files" ODB transaction, but the ODB
reprepare needs to remain the last step.

Lift ODB reprepare out of `flush_packfile_transaction()` and instead
require callers to explicitly invoke `odb_reprepare()` if required.

Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/object-file.c b/object-file.c
index a4cbf8b..0f123b7 100644
--- a/object-file.c
+++ b/object-file.c
@@ -857,8 +857,6 @@ static void flush_packfile_transaction(struct odb_transaction_files *transaction
 	memset(state, 0, sizeof(*state));
 
 	strbuf_release(&packname);
-	/* Make objects we just wrote available to ourselves */
-	odb_reprepare(repo->objects);
 }
 
 /*
@@ -909,8 +907,10 @@ static int odb_transaction_files_write_object_stream(struct odb_transaction *bas
 	 * to zlib compression and is sufficient for this check.
 	 */
 	if (state->nr_written && pack_size_limit_cfg &&
-	    pack_size_limit_cfg < state->offset + stream->size)
+	    pack_size_limit_cfg < state->offset + stream->size) {
 		flush_packfile_transaction(transaction);
+		odb_reprepare(transaction->base.source->odb);
+	}
 
 	CALLOC_ARRAY(idx, 1);
 	prepare_packfile_transaction(transaction);
@@ -1260,6 +1260,7 @@ static int odb_transaction_files_commit(struct odb_transaction *base)
 {
 	struct odb_transaction_files *transaction =
 		container_of(base, struct odb_transaction_files, base);
+	int have_packfile = !!transaction->packfile.f;
 
 	if (transaction->objdir) {
 		struct strbuf temp_path = STRBUF_INIT;
@@ -1293,6 +1294,9 @@ static int odb_transaction_files_commit(struct odb_transaction *base)
 
 	flush_packfile_transaction(transaction);
 
+	if (have_packfile)
+		odb_reprepare(transaction->base.source->odb);
+
 	return 0;
 }