Merge branch 'tg/checkout-no-overlay'

"git checkout --no-overlay" can be used to trigger a new mode of
checking out paths out of the tree-ish, that allows paths that
match the pathspec that are in the current index and working tree
and are not in the tree-ish.

* tg/checkout-no-overlay:
  revert "checkout: introduce checkout.overlayMode config"
  checkout: introduce checkout.overlayMode config
  checkout: introduce --{,no-}overlay option
  checkout: factor out mark_cache_entry_for_checkout function
  checkout: clarify comment
  read-cache: add invalidate parameter to remove_marked_cache_entries
  entry: support CE_WT_REMOVE flag in checkout_entry
  entry: factor out unlink_entry function
  move worktree tests to t24*

entry.c

@@ -441,6 +441,17 @@ int checkout_entry(struct cache_entry *ce, const struct checkout *state,
 	static struct strbuf path = STRBUF_INIT;
 	struct stat st;
 
+	if (ce->ce_flags & CE_WT_REMOVE) {
+		if (topath)
+			/*
+			 * No content and thus no path to create, so we have
+			 * no pathname to return.
+			 */
+			BUG("Can't remove entry to a path");
+		unlink_entry(ce);
+		return 0;
+	}
+
 	if (topath)
 		return write_entry(ce, topath, state, 1);
 
@@ -510,3 +521,18 @@ int checkout_entry(struct cache_entry *ce, const struct checkout *state,
 		(*nr_checkouts)++;
 	return write_entry(ce, path.buf, state, 0);
 }
+
+void unlink_entry(const struct cache_entry *ce)
+{
+	const struct submodule *sub = submodule_from_ce(ce);
+	if (sub) {
+		/* state.force is set at the caller. */
+		submodule_move_head(ce->name, "HEAD", NULL,
+				    SUBMODULE_MOVE_HEAD_FORCE);
+	}
+	if (!check_leading_path(ce->name, ce_namelen(ce)))
+		return;
+	if (remove_or_warn(ce->ce_mode, ce->name))
+		return;
+	schedule_dir_for_removal(ce->name, ce_namelen(ce));
+}