The "img" slot on <b-card> component doesn't render associated image

I am using <b-card> component with an image and some text. Here is my original markup:

<b-card
   ...
   img-src="some_url">
   <p>
      some text
   </p
</b-card>

it works fine, but when I try moving image into a separate slot like this:

<b-card
   ...>
   <div slot="img">
      <img src="some_url"/>
   </div>
   <p>
      some text
   </p
</b-card>

it doesn’t render the image, only text and other content that I omitted in this example.

[Branksy]

This should ideally be in the docs

[tmorehouse]

The img slot was only in the alpha branch (pre version 1.0.0.beta)