dependsOn and overwrite conflict

build.gradle

task a << {
    println 'task a'
}

task b(dependsOn: {a}) << { // works
// task b(dependsOn: 'a') << { // works
// task b(dependsOn: [a]) << { // doesn't work
// task b(dependsOn: a) << { // doesn't work
// task b << {
    println 'task b'
}

// b.dependsOn a // doesn't work
// b.dependsOn 'a' // works
// b.dependsOn {a} // works

task a(overwrite: true) << {
    println 'overwrite task a'
}