commands: remove suggestion to clone via `cp -al`

This was added in 2df98f616645 in 2006. This may be possible but it
seems like a bad idea to even suggest it.

Differential Revision: https://phab.mercurial-scm.org/D863

mercurial/commands.py

@@ -1339,18 +1339,6 b' def clone(ui, source, dest=None, **opts)'
       incorrectly, but do not report errors. In these cases, use the
       --pull option to avoid hardlinking.
 
-      In some cases, you can clone repositories and the working
-      directory using full hardlinks with ::
-
-        $ cp -al REPO REPOCLONE
-
-      This is the fastest way to clone, but it is not always safe. The
-      operation is not atomic (making sure REPO is not modified during
-      the operation is up to you) and you have to make sure your
-      editor breaks hardlinks (Emacs and most Linux Kernel tools do
-      so). Also, this is not compatible with certain extensions that
-      place their metadata under the .hg directory, such as mq.
-
       Mercurial will update the working directory to the first applicable
       revision from this list: