title: cmake ignores -D CMAKE_BUILD_TYPE=Debug
body: <p>I'm just trying to build a cmake project in debug-mode to enable asserts. I tried the following versions:</p>
  
  <pre><code>cmake -D CMAKE_BUILD_TYPE:STRING=Debug -L ../../
  cmake -DCMAKE_BUILD_TYPE:STRING=Debug -L ../../
  cmake -DCMAKE_BUILD_TYPE=Debug -L ../../
  </code></pre>
  
  <p>Unfortunately none of theese has the desired effect - that <code>CMAKE_BUILD_TYPE</code> is set to <code>Debug</code> (and therefore the <code>NDEBUG</code>-flag is not passed to gcc).</p>
  
  <p>Additionally I added <code>variable_watch(CMAKE_BUILD_TYPE)</code> to my main <code>CMakeLists.txt</code> to check whether the value get's overridden somewhere. But the first output is a <code>READ_ACCESS</code> in my main 
  Additionally I added <code>variable_watch(CMAKE_BUILD_TYPE)</code> to my main <code>CMakeLists.txt</code> and the value there already is <code>Release</code>.</p>
  
  <p>Does someone have an idea why cmake ignores the configuration?</p>
  
  <p>I'm using cmake version 2.8.7.</p>