commit-graph: close_commit_graph before shallow walk

Call close_commit_graph() when about to start a rev-list walk that
includes shallow commits. This is necessary in code paths that "fake"
shallow commits for the sake of fetch. Specifically, test 351 in
t5500-fetch-pack.sh runs

	git fetch --shallow-exclude one origin

with a file-based transfer. When the "remote" has a commit-graph, we do
not prevent the commit-graph from being loaded, but then the commits are
intended to be dynamically transferred into shallow commits during
get_shallow_commits_by_rev_list(). By closing the commit-graph before
this call, we prevent this interaction.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

commit-graph.c

@@ -260,10 +260,10 @@ static int prepare_commit_graph(struct repository *r)
 	return !!r->objects->commit_graph;
 }
 
-static void close_commit_graph(void)
+void close_commit_graph(struct repository *r)
 {
-	free_commit_graph(the_repository->objects->commit_graph);
-	the_repository->objects->commit_graph = NULL;
+	free_commit_graph(r->objects->commit_graph);
+	r->objects->commit_graph = NULL;
 }
 
 static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
@@ -875,7 +875,7 @@ void write_commit_graph(const char *obj_dir,
 	write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr);
 	write_graph_chunk_large_edges(f, commits.list, commits.nr);
 
-	close_commit_graph();
+	close_commit_graph(the_repository);
 	finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
 	commit_lock_file(&lk);
 

commit-graph.h

@@ -59,6 +59,7 @@ void write_commit_graph(const char *obj_dir,
 
 int verify_commit_graph(struct repository *r, struct commit_graph *g);
 
+void close_commit_graph(struct repository *);
 void free_commit_graph(struct commit_graph *);
 
 #endif

upload-pack.c

@@ -24,6 +24,7 @@
 #include "quote.h"
 #include "upload-pack.h"
 #include "serve.h"
+#include "commit-graph.h"
 
 /* Remember to update object flag allocation in object.h */
 #define THEY_HAVE	(1u << 11)
@@ -740,6 +741,7 @@ static void deepen_by_rev_list(int ac, const char **av,
 {
 	struct commit_list *result;
 
+	close_commit_graph(the_repository);
 	result = get_shallow_commits_by_rev_list(ac, av, SHALLOW, NOT_SHALLOW);
 	send_shallow(result);
 	free_commit_list(result);