Recent Jenkins releases have stopped detecting the test results produced by android-maven-plugin. This seems to be due to the refactoring done as part of the fix for JENKINS-8334.

After digging into the failure the problem is due to the reportsDir fallback code that gets executed if the mojo does not support a reportsDirectory config value.

Specifically (from SurefireArchiver.java and now TestMojo.java)

if (reportsDir == null) {
   // if test mojo doesn't have such config value, still almost all
   // default to target/surefire-reports
   reportsDir = new File(pom.getBasedir(),
         pom.getBuild().getDirectory()+File.separator+"surefire-reports");
   return true;
}

The code was moved between files during the fix but was not altered. It looks like the maven-android-plugin code is now falling through to that
and exposing a bug in the old code.

Basically pom.getBuild().getDirectory() returns a full path to the build directory and not just the bare directory name (usually "target").
See http://stackoverflow.com/questions/9318935/get-project-build-directory-from-mavenproject

I have tested a proposed fix (pull request coming soon) and it works in my environment.