fetch-pack: move common check and marking together

When receiving 'ACK <object-id> continue' for a common commit, check if
the commit was already known to be common and mark it as such if not up
front. This should make future refactoring of how the information about
common commits is stored more straightforward.

No visible change intended.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

fetch-pack.c

@@ -505,11 +505,14 @@ static int find_common(struct negotiation_state *ns,
 				case ACK_continue: {
 					struct commit *commit =
 						lookup_commit(result_oid);
+					int was_common;
 					if (!commit)
 						die(_("invalid commit %s"), oid_to_hex(result_oid));
+					was_common = commit->object.flags & COMMON;
+					mark_common(ns, commit, 0, 1);
 					if (args->stateless_rpc
 					 && ack == ACK_common
-					 && !(commit->object.flags & COMMON)) {
+					 && !was_common) {
 						/* We need to replay the have for this object
 						 * on the next RPC request so the peer knows
 						 * it is in common with us.
@@ -526,7 +529,6 @@ static int find_common(struct negotiation_state *ns,
 					} else if (!args->stateless_rpc
 						   || ack != ACK_common)
 						in_vain = 0;
-					mark_common(ns, commit, 0, 1);
 					retval = 0;
 					got_continue = 1;
 					if (ack == ACK_ready)