paymod: Update step before creating child payments

The child payments will sometimes depend on the step of the parent, and making
sure that the parent state is correct before we create the children is
therefore important.

plugins/libplugin-pay.c

@@ -1607,9 +1607,9 @@ static inline void retry_step_cb(struct retry_mod_data *rd,
 
 	/* If the failure was not final, and we tried a route, try again. */
 	if (rdata->retries > 0) {
+		payment_set_step(p, PAYMENT_STEP_RETRY);
 		subpayment = payment_new(p, NULL, p, p->modifiers);
 		payment_start(subpayment);
-		payment_set_step(p, PAYMENT_STEP_RETRY);
 		subpayment->why =
 		    tal_fmt(subpayment, "Still have %d attempts left",
 			    rdata->retries - 1);
@@ -2600,6 +2600,7 @@ static void presplit_cb(struct presplit_mod_data *d, struct payment *p)
 		if (amount_msat_greater(target, p->amount))
 			return payment_continue(p);
 
+		payment_set_step(p, PAYMENT_STEP_SPLIT);
 		/* Ok, we know we should split, so split here and then skip this
 		 * payment and start the children instead. */
 		while (!amount_msat_eq(amt, AMOUNT_MSAT(0))) {
@@ -2636,7 +2637,6 @@ static void presplit_cb(struct presplit_mod_data *d, struct payment *p)
 		    count,
 		    type_to_string(tmpctx, struct amount_msat, &root->amount),
 		    type_to_string(tmpctx, struct amount_msat, &target));
-		payment_set_step(p, PAYMENT_STEP_SPLIT);
 		plugin_log(p->plugin, LOG_INFORM, "%s", p->why);
 	}
 	payment_continue(p);
@@ -2734,6 +2734,7 @@ static void adaptive_splitter_cb(struct adaptive_split_mod_data *d, struct payme
 				    "allowed by our channels");
 			}
 
+			p->step = PAYMENT_STEP_SPLIT;
 			a = payment_new(p, NULL, p, p->modifiers);
 			b = payment_new(p, NULL, p, p->modifiers);
 
@@ -2758,7 +2759,6 @@ static void adaptive_splitter_cb(struct adaptive_split_mod_data *d, struct payme
 
 			payment_start(a);
 			payment_start(b);
-			p->step = PAYMENT_STEP_SPLIT;
 
 			/* Take note that we now have an additional split that
 			 * may end up using an HTLC. */