Unfinished/unreleased software changes are inventory. Inventory is a cost without a benefit.

From Deming's "Out of the Crisis", talking about Americans' experience visiting Japanese auto plants in the 1980s:

"Shipments of stampings, subassemblies and assemblies are made directly to the auto assembly line several times a day. Side-loading trucks drive into the assembly plant and containers of parts are dropped off at the appropriate work-station on the line without incoming inspection and counting. Parts are assembled into the automobiles, as received. The virtual absence of inventory results in an estimated space saving of 30 per cent as compared with comparable U.S. auto operations."