title: Buildbot multiple slaves working on same directory efficiently
body: <p>I am using "buildbot" to accommodate some git projects, however I cannot seem to write it in an efficient manner. Lets say I have a project named "Project" and have 3 different componenets within them namely "A", "B", "C" and have three different builders for them namely "Builder_A", "Builder_B", "Builder_C". Currently the scripts for the builders are almost same, except they are building different components within them. Here is my sample build routine for each builder.</p>
  
  <pre><code>make clean
  git checkout
  make 
  run sample tests
  </code></pre>
  
  <p>The problem occurs at git checkout, each bot is doing this step separately. However, if only one did this step it would be better in performance. How can I achieve this? Thanks in advance.</p>