commit-graph: free graph struct that was not added to chain

When reading the graph chain file, we open (and allocate) each
individual slice it mentions and then add them to a linked-list chain.
But if adding to the chain fails (e.g., because the base-graph chunk it
contains didn't match what we expected), we leave the function without
freeing the graph struct that caused the failure, leaking it.

We can fix it by calling free_graph_commit().

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: peff

commit-graph.c

@@ -566,6 +566,8 @@ static struct commit_graph *load_commit_graph_chain(struct repository *r,
 				if (add_graph_to_chain(g, graph_chain, oids, i)) {
 					graph_chain = g;
 					valid = 1;
+				} else {
+					free_commit_graph(g);
 				}
 
 				break;