query.empty() shouldn't add LIMIT 1 if query is marked as forUpdate()

[abishai]

query.empty() check adds LIMIT 1 to query, so information about row locking is lost (only 1 pseudo-random row will be locked).
For example,

            val query = Securities.select { Securities.lot eq 2 }.forUpdate()
            if (!query.empty()) {
                Securities.update({ query.where!! }) {
                    it[lot] = 1
                }
            }

produces

SELECT securities.id, securities."class", securities.ticker, securities.lot, securities.up_limit, securities.low_limit, securities.step FROM securities WHERE securities.lot = 2 LIMIT 1 FOR UPDATE
UPDATE securities SET lot=1 WHERE securities.lot = 2

So, we can expect that server will lock only 1 row, while it is possible that query affects more that one.
https://www.postgresql.org/docs/12/sql-select.html#SQL-FOR-UPDATE-SHARE

If a LIMIT is used, locking stops once enough rows have been returned to satisfy the limit

This can lead to hardly reproducible errors.

Suggestion: check if query has forUpdate() flag and leave query unaltered.