When you checkout the REL_1.0-mileston-6 tag from Github, then do './gradlew assemble', it gets a compilation error in the 'compileGroovy' task of coreImpl.

Output here:

gradle.git [(REL_1.0-milestone-6)]$ ./gradlew assemble
:buildSrc:compileJava UP-TO-DATE

[lots of UP-TO-DATE sections skipped for brevity]

:codeQuality:jar UP-TO-DATE
:coreImpl:classpathManifest UP-TO-DATE
:coreImpl:compileJava UP-TO-DATE
:coreImpl:compileGroovy
[ant:groovyc] org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
[ant:groovyc] Compile error during compilation with javac.
[ant:groovyc] /Users/robertdw/tmp/gradle.git/gradle.git/subprojects/core-impl/src/main/groovy/org/gradle/api/internal/artifacts/DefaultDependencyManagementServices.java:116: cannot find symbol
[ant:groovyc] symbol : constructor DefaultDependencyFactory(java.util.Set<org.gradle.api.internal.artifacts.dsl.dependencies.IDependencyImplementationFactory>,org.gradle.api.internal.artifacts.dsl.dependencies.DefaultClientModuleFactory,org.gradle.api.internal.artifacts.dsl.dependencies.DefaultProjectDependencyFactory)
[ant:groovyc] location: class org.gradle.api.internal.artifacts.DefaultDependencyFactory
[ant:groovyc] return new DefaultDependencyFactory(
[ant:groovyc] ^

[bunch of warnings about unchecked casts deleted for brevity]

[ant:groovyc] Note: Some input files use or override a deprecated API.
[ant:groovyc] Note: Recompile with -Xlint:deprecation for details.
[ant:groovyc] 1 error
[ant:groovyc] 7 warnings
[ant:groovyc]
[ant:groovyc]
[ant:groovyc] 1 error
[ant:groovyc]

FAILURE: Build failed with an exception.

• What went wrong:
  Execution failed for task ':coreImpl:compileGroovy'.
  Cause: Forked groovyc returned error code: 1

• Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED