title: How can I use git as the scm provider in sonarqube 5.0 ( using sonar-runner )
body: <p>I following the official support of sonarqub
  <a href="http://docs.sonarqube.org/display/SONAR/SCM+support">http://docs.sonarqube.org/display/SONAR/SCM+support</a></p>
  
  <p>and I got the error at above.</p>
  
  <p>did I miss something need to config, or configure wrong</p>
  
  <pre><code>08:46:33.723 INFO - Sensor SCM Sensor...
  08:46:33.897 INFO - SCM provider for this project is: git
  08:46:33.898 INFO - Retrieve SCM blame information...
  08:46:33.915 INFO - 632 files to be analyzed
  08:46:34.377 INFO - Author: PersonIdent[Not Committed Yet, , Tue Feb 3 08:46:34 2015 +0000]
  08:46:34.379 INFO - Source commit: null
  08:46:34.377 INFO - Author: PersonIdent[Not Committed Yet, , Tue Feb 3 08:46:34 2015 +0000]
  08:46:34.924 INFO - Source commit: null
  INFO: ------------------------------------------------------------------------
  INFO: EXECUTION FAILURE
  INFO: ------------------------------------------------------------------------
  Total time: 1:01.699s
  08:46:35.891 INFO - Author: PersonIdent[Not Committed Yet, , Tue Feb 3 08:46:35 2015 +0000]
  08:46:34.930 INFO - Author: PersonIdent[Not Committed Yet, , Tue Feb 3 08:46:34 2015 +0000]
  08:46:35.930 INFO - Source commit: null
  Final Memory: 27M/318M
  INFO: ------------------------------------------------------------------------
  ERROR: Error during Sonar runner execution
  ERROR: Unable to execute Sonar
  ERROR: Caused by: Unable to blame file
  </code></pre>
  
  <p>thanks very much. </p>