unbroken but unfixed data path vs code path search conundrum

RU/ru_main.m

 function RU = ru_main(sat_name,l1b_fname,saveTotalRU_FLAG,pname_out);
-userpath(getenv('RU_HOME'));
+% addpath and userpath will both BREAK compiled code. so this is forbidden:
+%   userpath(getenv('RU_HOME'));
+% however, we need a way for RU instrument ref data files to load from $RU_HOME by default
 RU = cris_gran_RU_ncparam(sat_name,l1b_fname,saveTotalRU_FLAG,pname_out);
 return