diff -r d549cfeb5bf7 -r 4de15c54e59f mercurial/commands.py
--- a/mercurial/commands.py	Fri Mar 02 15:48:31 2018 -0500
+++ b/mercurial/commands.py	Thu Feb 08 23:27:24 2018 +0530
@@ -1326,8 +1326,10 @@
                                'directory (only a repository)')),
     ('u', 'updaterev', '', _('revision, tag, or branch to check out'),
         _('REV')),
-    ('r', 'rev', [], _('include the specified changeset'), _('REV')),
-    ('b', 'branch', [], _('clone only the specified branch'), _('BRANCH')),
+    ('r', 'rev', [], _('do not clone everything, but include this changeset'
+                       ' and its ancestors'), _('REV')),
+    ('b', 'branch', [], _('do not clone everything, but include this branch\'s'
+                          ' changesets and their ancestors'), _('BRANCH')),
     ('', 'pull', None, _('use pull protocol to copy metadata')),
     ('', 'uncompressed', None,
        _('an alias to --stream (DEPRECATED)')),