[1.9-rc-1] IllegalStateException: org.slf4j.LoggerFactory could not be successfully initialized

Building sulky with Gradle 1.9-rc-1 causes exceptions while 1.8 works fine.

The exception says ‘org.slf4j.LoggerFactory could not be successfully initialized. See also http://www.slf4j.org/codes.html#unsuccessfulInit’ but there is no corresponding information available on the referenced slf4j-page.

All of my subprojects have the following dependencies applied: ‘’'groovy dependencies {

testCompile libraries.‘groovy’

testCompile libraries.‘spock-core’

testCompile libraries.junit

testCompile libraries.‘slf4j-api’

testRuntime libraries.‘logback-classic’ } ‘’’

Both slf4j and logback are using the latest version, i.e. slf4j 1.7.5 and logback 1.0.13.

The exception is thrown while the tests are executed.