Revert "git stash: avoid data loss when "git stash save" kills a directory"

This reverts commit a73653130e, as it
has been reported that "ls-files --killed" is too time-consuming in
a deep directory with too many untracked crufts (e.g. $HOME/.git
tracking only a few files).

We'd need to revisit it later but "ls-files --killed" needs to be
optimized before it happens.

Documentation/git-stash.txt

@@ -14,8 +14,7 @@ SYNOPSIS
 'git stash' ( pop | apply ) [--index] [-q|--quiet] [<stash>]
 'git stash' branch <branchname> [<stash>]
 'git stash' [save [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]
-	     [-u|--include-untracked] [-a|--all] [-f|--force]
-	     [<message>]]
+	     [-u|--include-untracked] [-a|--all] [<message>]]
 'git stash' clear
 'git stash' create [<message>]
 'git stash' store [-m|--message <message>] [-q|--quiet] <commit>
@@ -45,7 +44,7 @@ is also possible).
 OPTIONS
 -------
 
-save [-p|--patch] [--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [-f|--force] [<message>]::
+save [-p|--patch] [--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [<message>]::
 
 	Save your local modifications to a new 'stash', and run `git reset
 	--hard` to revert them.  The <message> part is optional and gives
@@ -72,13 +71,6 @@ linkgit:git-add[1] to learn how to operate the `--patch` mode.
 +
 The `--patch` option implies `--keep-index`.  You can use
 `--no-keep-index` to override this.
-+
-In some cases, saving a stash could mean irretrievably removing some
-data - if a directory with untracked files replaces a tracked file of
-the same name, the new untracked files are not saved (except in case
-of `--include-untracked`) but the original tracked file shall be restored.
-By default, `stash save` will abort in such a case; `--force` will allow
-it to remove the untracked files.
 
 list [<options>]::