gradle problem in f{19,20}

[gil]

hi
groovy 2.x series  (and other libraries) require gradle for build, but 
with gradle there is a problem I tried to solve without success in f19 
and f20 (in f18 work fine :( ).
(the same happen when rebuild gradle in non bootstrap mode)

gradle --debug jar javadoc -g 
/builddir/build/BUILD/hibernate-release-4.1.7.Final/gradlehome -b 
/builddir/build/BUILD/hibernate-release-4.1.7.Final/buildSrc/build.gradle
10:28:52.228 [DEBUG] 
[org.gradle.logging.internal.DefaultLoggingConfigurer] Finished 
configuring with level: DEBUG, configurers: 
[org.gradle.logging.internal.OutputEventRenderer at 14bd4d1, 
org.gradle.logging.internal.slf4j.Slf4jLoggingConfigurer at 180fd99, 
org.gradle.logging.internal.JavaUtilLoggingConfigurer at 18955ea]
10:28:52.282 [ERROR] [org.gradle.BuildExceptionReporter]
10:28:52.284 [ERROR] [org.gradle.BuildExceptionReporter] FAILURE: Build 
aborted because of an internal error.
10:28:52.287 [ERROR] [org.gradle.BuildExceptionReporter]
10:28:52.288 [ERROR] [org.gradle.BuildExceptionReporter] * What went wrong:
10:28:52.290 [ERROR] [org.gradle.BuildExceptionReporter] Build aborted 
because of an unexpected internal error. Please file an issue at: 
http://forums.gradle.org
the same using -S (--full-stacktrace) parameter.
any ideas?
thanks
- gil