diff -r f3dca85bd2d1 -r c75c8ea2f573 mercurial/commands.py
--- a/mercurial/commands.py	Fri Jun 10 10:31:42 2016 +0200
+++ b/mercurial/commands.py	Mon Jun 20 23:24:55 2016 +0200
@@ -5784,6 +5784,9 @@
     If SOURCE is omitted, the 'default' path will be used.
     See :hg:`help urls` for more information.
 
+    Specifying bookmark as ``.`` is equivalent to specifying the active
+    bookmark's name.
+
     Returns 0 on success, 1 if an update had unresolved files.
     """
     source, branches = hg.parseurl(ui.expandpath(source), opts.get('branch'))