Prune the QP prefix sub-branch search more efficiently.

src/qp.c

@@ -458,15 +458,14 @@ QP_Prefixes(const struct qp_y * const restrict root,
 				continue;
 			yy = y->branch[i];
 			CHECK_OBJ_NOTNULL(yy, QP_Y_MAGIC);
-			if (yy->off + yy-> len != l)
+			if (!yy->term || yy->off + yy-> len != l)
 				continue;
-			if (yy->term) {
-				if (strncmp(subject, strings[yy->idx], l) != 0)
-					return (0);
-				assert(l != len);
-				if (update_match(match, yy->idx, len, l) != 0)
-					return (-1);
-			}
+			if (strncmp(subject, strings[yy->idx], l) != 0)
+				return (0);
+			assert(l != len);
+			if (update_match(match, yy->idx, len, l) != 0)
+				return (-1);
+			break;
 		}
 
 		if (idx == -1)