Not so much lines for bread but more special items that ran out quickly, the USSR had plenty of bread and sausage coming out of state-owned bakeries on the cheap. Complaints about shortages were about things they mostly had to trade for like sugar, fruit, coffee, chocolate (the Cuban revolution was a godsend for the Soviets in that regard). Even then the lines were for the cheap subsidized versions of those products in the normal grocery stores. most of the time these were still available in special foreign imports stores, but obviously these were more expensive.