limitedParallelism does not propagate the full CoroutineContext to the underlying dispatcher

[dkhalanskyjb]

import kotlinx.coroutines.*
import kotlin.coroutines.*

object MyDispatcher: CoroutineDispatcher() {    
    override fun dispatch(context: CoroutineContext, block: Runnable) {
        println(context)
        block.run()
    }
}

fun main() {
    val newDispatcher = MyDispatcher.limitedParallelism(2)
    newDispatcher.dispatch(CoroutineName("Hi!"), Runnable { })
}

prints

LimitedDispatcher@4459eb14

No CoroutineName in sight.

https://pl.kotl.in/86W-MnSGn

This bug was not reported to us as any production issue, but was found accidentally by reading

kotlinx.coroutines/kotlinx-coroutines-core/common/src/internal/LimitedDispatcher.kt

Lines 43 to 54 in 6c6df2b

	override fun dispatch(context: CoroutineContext, block: Runnable) {
	dispatchInternal(block) { worker ->
	dispatcher.dispatch(this, worker)
	}
	}
	@InternalCoroutinesApi
	override fun dispatchYield(context: CoroutineContext, block: Runnable) {
	dispatchInternal(block) { worker ->
	dispatcher.dispatchYield(this, worker)
	}
	}