Using ng-repeat variable inside src attribute in angularjs?

Question

I have the following:

div.container
    script(src='/js/bootstrap/holder.js')
    p.text-info(ng-pluralize,
                count="devices.length",
                when="{ '0': 'There are no fragments.', 'one': 'There is 1 fragment.', 'other': 'There are {} fragments.'}")

    ul.unstyled(ng-repeat='fragment in devices')
        ul.thumbnails
            li.span
                div.thumbnail
                    img(src="holder.js/{{fragment.dimension.width}}x{{fragment.dimension.height}}")
                    div.caption
                        h3 {{fragment.name}}
                        p {{fragment.dimension}}
                        ul.unstyled(ng-repeat='component in fragment.components')
                            li {{ component.name }}

The problem is in src="holder.js/{{fragment.dimension.width}}x{{fragment.dimension.height}}", i.e. even if looking at the resulting html I see a correct src (src="holder.js/300x200") it does not show the image. My guess is this is not how one uses angular variables inside attributes..

How can I make it work?

EDIT: it seems it does not execute holder.js.. here is the source: in the first call I used angular {{hash}} in the second I manually put holder.js/300x200

<div class="thumbnail">
    <img src="holder.js/1678x638">
    <img src="data:image/png;base64,iVBORw0KG...ElFTkSuQmCC" data-src="holder.js/300x200" alt="300x200" style="width: 300px; height: 200px;">
</div>

Answer 1

The documentation explains that quite clearly:

Using Angular markup like {{hash}} in a src attribute doesn't work right: The browser will fetch from the URL with the literal text {{hash}} until Angular replaces the expression inside {{hash}}. The ngSrc directive solves this problem.

So you must use:

<img ng-src="holder.js/{{fragment.dimension.width}}x{{fragment.dimension.height}}" />