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 1262 matching lines @@
       *for modules which have changed since last update or sync*
   gclient sync --force
       update files from SCM according to current configuration, for
       all modules (useful for recovering files deleted from local copy)
   gclient sync --revision src@31000
       update src directory to r31000
 """)
 def CMDsync(parser, args):
   """Checkout/update all modules."""
   parser.add_option('-f', '--force', action='store_true',
-                    help='force update even for unchanged modules')
+                    help='Forces update even for unchanged modules. Also '
+                         'removes from the working copy directories which have '
+                         'been removed from the repository in this update and '
+                         'hence are untracked. Directories are removed even if '
+                         'explicitly ignored, to allow dependencies to be '
+                         'installed in their place.')
   parser.add_option('-n', '--nohooks', action='store_true',
                     help='don\'t run hooks after the update is complete')
   parser.add_option('-r', '--revision', action='append',
                     dest='revisions', metavar='REV', default=[],
                     help='Enforces revision/hash for the solutions with the '
                          'format src@rev. The src@ part is optional and can be '
                          'skipped. -r can be used multiple times when .gclient '
                          'has multiple solutions configured and will work even '
                          'if the src@ part is skipped. Note that specifying '
                          '--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.')
   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: