It's pretty standard across our code base... and it's also wrong when there are checkboxes present :(

With checkboxes present, request.POST can evaluate to a falsy value if the rest of the form is empty, because browsers don't send unchecked checkoxes in the POST data. But we want to differenciate that case from the form being requested via GET, else we wouldn't be able to uncheck the checkboxe(s) if the rest of the form is empty !

It's something I've been fixing in every view I found it (unless it wasn't necessary: sometimes the form cannot be valid & empty), but we might have some left still.