title: git commit --author doesn't work when global not set
body: <p>working on a lab machine which has a shared login.  don't want to set global git config parameters.  </p>
  
  <pre><code>git commit --author="username &lt;email&gt;" 
  </code></pre>
  
  <p>This used to work on older git versions. now it produces this error:</p>
  
  <pre><code>*** Please tell me who you are.
  
  Run
  
    git config --global user.email "you@example.com"
    git config --global user.name "Your Name"
  
  to set your account's default identity.
  Omit --global to set the identity only in this repository.
  
  fatal: unable to auto-detect email address (got 'blah@blah.(none)')
  </code></pre>
  
  <p>Any thoughts?</p>