Problem: If the lockfile points to the revision that is not on disk, the
`:checkhealth vim.pack` suggests to run `vim.pack.update()`. Although
usually it should resolve the problem, it is not always the case: like
if the state on disk is already the latest available.
Solution: Add an extra suggestion with a more drastic measure by
manually removing `rev` field from the lockfile for it to be repaired
after the `:restart`.
(cherry picked from commit 94c0e54e5b)
1a5d41a48f
