REBASE bump checkpoint
Revert "Better warning/"alert" messages for large-work forks."

This reverts commit 5a2acc03490567ba018de04bdeadb4e367fa372e.
Revert "Call the -alertnotify script when we see a long or invalid fork."

This reverts commit ce67f5ff45beeb3fd9c67a07e8ff802c13253a9e.
Revert "Detect any sufficiently long fork and add a warning."

This reverts commit 2b1a2e6508cbb30503efa2cb3fdc10edc4ae09f6.