If --force is specified when updating, remove unversioned directories

gclient.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Meta checkout manager supporting both Subversion and GIT.
 
 Files
   .gclient      : Current client configuration, written by 'config' command.
                   Format is a Python script defining 'solutions', a list whose
@@ skipping 1282 matching lines @@
                          '--revision means your safesync_url gets ignored.')
   parser.add_option('-t', '--transitive', action='store_true',
                     help='When a revision is specified (in the DEPS file or '
                           'with the command-line flag), transitively update '
                           'the dependencies to the date of the given revision. '
                           'Only supported for SVN repositories.')
   parser.add_option('-H', '--head', action='store_true',
                     help='skips any safesync_urls specified in '
                          'configured solutions and sync to head instead')
   parser.add_option('-D', '--delete_unversioned_trees', action='store_true',
-                    help='delete any dependency that have been removed from '
-                         'last sync as long as there is no local modification. '
-                         'Coupled with --force, it will remove them even with '
-                         'local modifications')
+                    help='Deletes from the working copy any dependencies that '
+                         'have been removed since the last sync, as long as '
+                         'there are no local modifications. When used with '
+                         '--force, such dependencies are removed even if they '
+                         'have local modifications. In addition, when used '
+                         'with --force, all untracked directories are removed '
+                         'from the working copy, exclusing those which are '
+                         'explicitly ignored in the repository.')
   parser.add_option('-R', '--reset', action='store_true',
                     help='resets any local changes before updating (git only)')
   parser.add_option('-M', '--merge', action='store_true',
                     help='merge upstream changes instead of trying to '
                          'fast-forward or rebase')
   parser.add_option('--deps', dest='deps_os', metavar='OS_LIST',
                     help='override deps for the specified (comma-separated) '
                          'platform(s); \'all\' will process all deps_os '
                          'references')
   parser.add_option('-m', '--manually_grab_svn_rev', action='store_true',
@@ skipping 215 matching lines @@
   except (gclient_utils.Error, subprocess2.CalledProcessError), e:
     print >> sys.stderr, 'Error: %s' % str(e)
     return 1
 
 
 if '__main__' == __name__:
   fix_encoding.fix_encoding()
   sys.exit(Main(sys.argv[1:]))
 
 # vim: ts=2:sw=2:tw=80:et: