lightningd: remove htlc_set destruction timer once we head to invoice.

Otherwise tests for hold_invoice fail on Travis (they use 180 / 2 as
the timeout, and we free it after 70 seconds).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/htlc_set.c

@@ -1,4 +1,3 @@
-#include <common/memleak.h>
 #include <common/timeout.h>
 #include <lightningd/htlc_end.h>
 #include <lightningd/htlc_set.h>
@@ -84,10 +83,12 @@ static struct htlc_set *new_htlc_set(struct lightningd *ld,
 	 *   - SHOULD wait for at least 60 seconds after the initial
 	 *     HTLC.
 	 */
-	notleak(new_reltimer(ld->timers, set, time_from_sec(70),
-			     timeout_htlc_set, set));
+	set->timeout = new_reltimer(ld->timers, set, time_from_sec(70),
+				    timeout_htlc_set, set);
 	htlc_set_map_add(&ld->htlc_sets, set);
 	tal_add_destructor2(set, destroy_htlc_set, &ld->htlc_sets);
+#else
+	set->timeout = NULL;
 #endif
 	return set;
 }
@@ -194,6 +195,8 @@ void htlc_set_add(struct lightningd *ld,
 	}
 
 	if (amount_msat_eq(set->so_far, total_msat)) {
+		/* Disable timer now, in case invoice_hook is slow! */
+		tal_free(set->timeout);
 		invoice_try_pay(ld, set, details);
 		return;
 	}

lightningd/htlc_set.h

@@ -17,6 +17,7 @@ struct htlc_set {
 	struct amount_msat total_msat, so_far;
 	struct sha256 payment_hash;
 	struct htlc_in **htlcs;
+	struct oneshot *timeout;
 };
 
 static inline const struct sha256 *keyof_htlc_set(const struct htlc_set *set)