25.8.15 Stable backport of #84770: Handle NULLs in ALTER MODIFY COLUMN#1344

zvonand wants to merge 2 commits intoreleases/25.8.15Altinity/ClickHouse:releases/25.8.15from

backports/25.8.15/84770Altinity/ClickHouse:backports/25.8.15/84770Copy head branch name to clipboard