Gradle 2.1 build from source failed with TaskExecutionException: reference to UncheckedIOException is ambiguous

On OS X 10.9.3, Oracle JDK 1.8.0_05, version.txt says 2.1.

Cloned git repo, tried to build with

./gradlew build


Build failed:

gradle/subprojects/plugin-use/src/main/java/org/gradle/plugin/use/resolve/service/internal/ error: reference to UncheckedIOException is ambiguous
            throw new UncheckedIOException(e);
  both class in and class org.gradle.api.UncheckedIOException in org.gradle.api match
1 error
:pluginUse:compileJava FAILED
  FAILURE: Build failed with an exception.
  * What went wrong:
Execution failed for task ':pluginUse:compileJava'.
> Compilation failed; see the compiler error output for details.
  * Exception is:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':pluginUse:compileJava'.
 at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(
 at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(