Merge branch 'sb/submodule-core-worktree'

"git submodule" did not correctly adjust core.worktree setting that
indicates whether/where a submodule repository has its associated
working tree across various state transitions, which has been
corrected.

* sb/submodule-core-worktree:
  submodule deinit: unset core.worktree
  submodule: ensure core.worktree is set after update
  submodule: unset core.worktree if no working tree is present

diff --cc builtin/submodule--helper.c
Simple merge

diff --cc git-submodule.sh
Simple merge

diff --cc submodule.c
Simple merge

diff --cc t/t7400-submodule-basic.sh
Simple merge