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

git-submodule.sh

@@ -577,6 +577,11 @@ cmd_update()
 			die "$(eval_gettext "Unable to find current \${remote_name}/\${branch} revision in submodule path '\$sm_path'")"
 		fi
 
+		if ! $(git config -f "$(git rev-parse --git-common-dir)/modules/$name/config" core.worktree) 2>/dev/null
+		then
+			git submodule--helper connect-gitdir-workingtree "$name" "$sm_path"
+		fi
+
 		if test "$subsha1" != "$sha1" || test -n "$force"
 		then
 			subforce=$force