Test 'RemoteSandboxForTesting should include tools.jar in the classpath for ant projects' fails when running tests with Java 8

Running the test suite with JDK 8 gives the following error

Failures:

  1) RemoteSandboxForTesting should include tools.jar in the classpath for ant projects
     Failure/Error: Unable to find matching line from backtrace
     CourseRefresher::Failure:
       warning: Supported source version 'RELEASE_6' from annotation processor 'fi.helsinki.cs.tmc.testscanner.TestMethodAnnotationProcessor' less than -source '1.8'
       /home/tmc/tmc-langs/tmc-server/tmp/tests/cache/git_repos/MyCourse-1/clone/UsingToolsJar/test/SimpleTest.java:5: error: package sun.tools.native2ascii does not exist
       import sun.tools.native2ascii.Main; // Requires tools.jar
                                    ^
       1 error
       1 warning
       Exception in thread "main" java.lang.RuntimeException: Compilation failed
        at fi.helsinki.cs.tmc.testscanner.TestScanner.findTests(TestScanner.java:137)
        at fi.helsinki.cs.tmc.testscanner.TestScanner.main(TestScanner.java:39)

Failed examples:

rspec ./spec/integration/running_tests/general_spec.rb:99 # RemoteSandboxForTesting should include tools.jar in the classpath for ant projects