Remind staff about potential issue when reducing number of copies available for loans.

[mhucka]

There can arise an awkward situation when editing item entries. If you reduce the number of available copies of an item (from some number $M$ to $N$, where $N < M$), and at the time you do it, there are loans out on all available copies (all $M$), then temporarily there will be more copies loaned than the new permitted number of loans ($N$). This will persist until some loans expire; more precisely, until $M - N$ loans expire. DIBS does it this way because the alternative would be to terminate $M - N$ loans forcefully. Not only would that be frustrating for users (who would experience loans ending before the time they were promised); it would also lead to the question of how to decide fairly which loans to terminate. The current approach in DIBS is probably a reasonable tradeoff when loan durations are short, but for long loan durations (say, longer than a day), staff should make sure to wait until the number of loans has dropped to $N$ or less before putting physical copies back into circulation, to avoid the possibility that there are more digital copies on loan than have been pulled from physical circulation.

The editing page could put up a warning dialog to remind staff about this.