It worked a couple days ago. I did update the android sdk since the last successful build. It's up to date now.

Creating full resource package...

     [aapt] /tmp/android2756627430951891773sketch/assets/Metrics/images/com.stateofflow.eclipse.metrics.calculators.cohesion.LackOfCohesionInMethodsCalculator.chidamberKemerer.jpg: error: Invalid filename.  Unable to add.

BUILD FAILED

/opt/android-sdk-linux/tools/ant/build.xml:921: The following error occurred while executing this line:

/opt/android-sdk-linux/tools/ant/build.xml:939: null returned: 1