title: Error during SonarQube Scanner execution with sonar python enabled
body: <p>I am a very new sonarqube user, experimenting with my python project. </p>
  
  <p>I have installed docker Sonarqube image which has Sonarpython plugin installed. I installed the linux base sonar scanner.</p>
  
  <p>Using <a href="https://docs.sonarqube.org/display/SCAN/Analyzing+with+SonarQube+Scanner" rel="nofollow noreferrer">these</a> instructions, I configured the scanner.</p>
  
  <p>However when running it, I run into:</p>
  
  <pre><code>11:28:33.486 INFO: Configured Java source version (sonar.java.source): none
  11:28:33.496 INFO: JavaClasspath initialization
  11:28:33.512 INFO: ------------------------------------------------------------------------
  11:28:33.512 INFO: EXECUTION FAILURE
  11:28:33.512 INFO: ------------------------------------------------------------------------
  11:28:33.513 INFO: Total time: 22.237s
  11:28:33.670 INFO: Final Memory: 28M/509M
  11:28:33.671 INFO: ------------------------------------------------------------------------
  11:28:33.671 ERROR: Error during SonarQube Scanner execution
  org.sonar.java.AnalysisException: Please provide compiled classes of your project with sonar.java.binaries property
      at org.sonar.java.JavaClasspath.init(JavaClasspath.java:66)
      at org.sonar.java.AbstractJavaClasspath.getElements(AbstractJavaClasspath.java:280)
      at org.sonar.java.SonarComponents.getJavaClasspath(SonarComponents.java:175)
      at org.sonar.java.JavaSquid.&lt;init&gt;(JavaSquid.java:82)
      at org.sonar.plugins.java.JavaSquidSensor.execute(JavaSquidSensor.java:91)
      at org.sonar.scanner.sensor.AbstractSensorWrapper.analyse(AbstractSensorWrapper.java:48)
      at org.sonar.scanner.sensor.ModuleSensorsExecutor.execute(ModuleSensorsExecutor.java:85)
      at org.sonar.scanner.sensor.ModuleSensorsExecutor.lambda$execute$1(ModuleSensorsExecutor.java:59)
      at org.sonar.scanner.sensor.ModuleSensorsExecutor.withModuleStrategy(ModuleSensorsExecutor.java:77)
      at org.sonar.scanner.sensor.ModuleSensorsExecutor.execute(ModuleSensorsExecutor.java:59)
      at org.sonar.scanner.scan.ModuleScanContainer.doAfterStart(ModuleScanContainer.java:82)
      at org.sonar.core.platform.ComponentContainer.startComponents(ComponentContainer.java:136)
      at org.sonar.core.platform.ComponentContainer.execute(ComponentContainer.java:122)
      at org.sonar.scanner.scan.ProjectScanContainer.scan(ProjectScanContainer.java:359)
      at org.sonar.scanner.scan.ProjectScanContainer.scanRecursively(ProjectScanContainer.java:354)
      at org.sonar.scanner.scan.ProjectScanContainer.doAfterStart(ProjectScanContainer.java:317)
      at org.sonar.core.platform.ComponentContainer.startComponents(ComponentContainer.java:136)
      at org.sonar.core.platform.ComponentContainer.execute(ComponentContainer.java:122)
      at org.sonar.scanner.bootstrap.GlobalContainer.doAfterStart(GlobalContainer.java:128)
      at org.sonar.core.platform.ComponentContainer.startComponents(ComponentContainer.java:136)
      at org.sonar.core.platform.ComponentContainer.execute(ComponentContainer.java:122)
      at org.sonar.batch.bootstrapper.Batch.doExecute(Batch.java:73)
      at org.sonar.batch.bootstrapper.Batch.execute(Batch.java:67)
      at org.sonarsource.scanner.api.internal.batch.BatchIsolatedLauncher.execute(BatchIsolatedLauncher.java:46)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:498)
      at org.sonarsource.scanner.api.internal.IsolatedLauncherProxy.invoke(IsolatedLauncherProxy.java:60)
      at com.sun.proxy.$Proxy0.execute(Unknown Source)
      at org.sonarsource.scanner.api.EmbeddedScanner.doExecute(EmbeddedScanner.java:185)
      at org.sonarsource.scanner.api.EmbeddedScanner.execute(EmbeddedScanner.java:137)
      at org.sonarsource.scanner.cli.Main.execute(Main.java:111)
      at org.sonarsource.scanner.cli.Main.execute(Main.java:75)
      at org.sonarsource.scanner.cli.Main.main(Main.java:61)
  </code></pre>
  
  <p>Do I need to configure <code>sonar.java.source</code> to successfully scan?</p>