title: What is the meaning of :/ (colon, forward slash) in the 2.0 version of git add --update syntax?
body: <p>I upgraded Git a couple months ago and since then I've been receiving the following deprecation notice upon attempting <code>git add --update</code>:</p>
  
  <blockquote>
    <p>Warning: The behavior of 'git add --update (or -u)' with no path
    argument from a subdirectory of the tree will change in Git 2.0 and
    should not be used anymore. To add content for the whole tree, run:</p>
    
    <p>git add --update :/   (or git add -u :/)</p>
    
    <p>To restrict the command to the current directory, run:</p>
    
    <p>git add --update .   (or git add -u .)</p>
    
    <p>With the current Git version, the command is restricted to the current
    directory.</p>
  </blockquote>
  
  <p>The warning itself makes perfectly good sense, and it's saved me some resetting. I've gotten used to typing the <code>.</code> or <code>:/</code>, but still find the latter quite strange because it's unlike any other command line syntax I've encountered. The <code>.</code> is pretty token: it just means "current directory", like in <code>find .</code>, but <code>:/</code>... never seen that except in this context. What does it mean?</p>
  
  <p>I keep thinking of it as an emoticon, and certainly that's not the case?</p>