How to inherit slots with svelte components?

There is a component <Bar> that inherits from a component <Foo>.

The <Foo> component defines a slot named content with a fallback content. The <Bar> component also defines a slot named content with a different fallback content.

<!-- Foo.svelte -->
<slot name="content">
  foo fallback
</slot> 

<!-- Bar.svelte -->
<script>import Foo from './Foo.svelte'</script>
<Foo>
    <span slot="content">
        bar fallback
    </span>
</Foo>

The <Bar> component displays the fallback when called with <Foo/> but it does not display the custom content when called with <Bar><span slot="content">bar custom</span></Bar>.

Can you tell me what I am doing wrong?

<Foo/>
<!-- prints 'foo fallback': OK -->

<Foo>
    <span slot="content">foo custom</span>
</Foo>
<!-- prints 'foo custom': OK -->

<Bar/>
<!-- prints 'bar fallback': OK -->

<Bar>
    <span slot="content">bar custom</span>
</Bar>
<!-- prints 'bar fallback': KO - I would have expected 'bar custom' -->

The fiddle: https://svelte.dev/repl/5c525651eb8b4f60a6a696c1bd19f723