mono { } with timeout never completes

[frost13it]

Expected behaviour:
When a coroutine inside mono { } fails with a TimeoutCancellationException, the returned Mono terminates with an error.

Actual behaviour:
The returned Mono never completes.

Example:

import kotlinx.coroutines.delay
import kotlinx.coroutines.reactor.mono
import kotlinx.coroutines.withTimeout

fun main() {
    val mono = mono {
        withTimeout(1) { delay(100) }
    }
    mono.doOnSubscribe { println("Subscribed") }
        .doOnNext { println("Emitted: $it") }
        .doOnSuccess { println("Completed") }
        .doOnError { println("Error: $it") }
        .doOnCancel { println("Cancelled") }
        .block()
    println("Done")
}

The code above prints Subscribed and hangs forever.

It seems that such behaviour is introduced in #1638.