[ic] total-cost function occasionally not including shipping

[Tom Friedel]

5.7.3 and very old catalog using txt database.   I see in the code 
mv_ship_mode must be set for shipping to be included in total-cost, but can 
not explain why 1/15 orders do not have mv_shipmode set when total-cost is 
called (my theory as to why total-cost occassionally returns value w/o 
shipping).  Data in database always correct, and a shipping method 
(mv_shipmode) is always selected.
thanks very much for any guesses
Tom Friedel