Image height is not taken into account when width is missing and rendering.imageDimensionsIncludedInImageURL = false

Steps to reproduce:
1. On the xwiki.properties of a wiki, set rendering.imageDimensionsIncludedInImageURL = false (the default is true).

2. Start the wiki server.
3. Add an image on a page.
4. Open the image editing dialogue > Advanced tab.
5. Add a height value (for example 250px) but keep the width field empty.

6. Save the image settings and page.

Expected result: the image will keep the set height
Actual result: the image is not keeping the set height (it's also still present in the html), it will take an automatic height because of an inherited CSS rule which is

height: auto;

that is set on all images from the skin.

Current workaround: add a value to the weight.