Gradle 3.0.0 alpha variant output issue

I want to have a different versionCode for debug build type rather than the one in release build type. This used to work by using the configuration from below in Gradle Android plugin v2.3.2 (Gradle v3.3), but doesn't have any effect now in v3.0.0-alpha5 (Gradle v4.1-milestone-1). Any ideas as to what changed in the newest Gradle plugin that makes it ignore the variant.mergedFlavor.versionCode attribute?

buildTypes {    
      debug {
                applicationIdSuffix ".debug"
                versionNameSuffix "-" + buildTime()
                android.applicationVariants.all { variant ->
                    if (variant.buildType.name != buildTypes.debug.name) return
                    variant.outputs.all {
                        outputFileName = "${archivesBaseName}-${variant.name}-v${variant.versionName}-signed.apk"
                        variant.mergedFlavor.versionCode = Integer.parseInt(buildTimeSmall())
                    }
                }
            }
}