Reset day length factor to 1 when loading pre day length savegame

src/saveload/afterload.cpp

@@ -694,6 +694,11 @@ bool AfterLoadGame()
 	/* The value of _date_fract got divided, so make sure that old games are converted correctly. */
 	if (IsSavegameVersionBefore(11, 1) || (IsSavegameVersionBefore(147) && _date_fract > DAY_TICKS)) _date_fract /= 885;
 
+	/* Set day length factor to 1 if loading a pre day length savegame */
+	if (SlXvIsFeatureMissing(XSLFI_VARIABLE_DAY_LENGTH)) {
+		_settings_game.economy.day_length_factor = 1;
+	}
+
 	/* Update current year
 	 * must be done before loading sprites as some newgrfs check it */
 	SetDate(_date, _date_fract);