Can't use thumbnail() with height only, and width set to None

According to the documentation the thumbnail function should support setting height ony. However, the build process complains that width is a required positional.

".../templates/blocks/image.html", line 4, in top-level template code
    <img src="{{ image.thumbnail(height=this.height)|url }}">
TypeError: thumbnail() missing 1 required positional argument: 'width'

Setting width to None does not work either:

File ".../site-packages/lektor/db.py", line 785, in thumbnail
    width = int(width)
TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

which is weird in itself, db.py line 785 points to a different line in master branch.

I’m using the latest 3.1.3 version installed just a few days ago.

[nixjdm]

Yes, the thumbnail API was changed quite a lot in the master branch and this issue shouldn’t exist any longer. The next release is pending a few remaining items on our checklist, but I don’t have an ETA for it. Just as soon as we can. In the meantime you may want to install from source with pip install -e .

[runfalk]

We are currently doing work to have a “stable” and “nightly” branch (or similar) of the docs. The first PR that ties docs directly to the code is here: https://github.com/lektor/lektor/pull/787.

This is mainly a problem since there hasn’t been a release in so long and I expect it to be less of a problem going forward.