Editing HtmlAreas wrongfully keeps non-breaking space

Enonic version: 6.15.5
OS: Windows 10

When editing text in an HtmlArea, the non-breaking space   is kept, even though the new edited text actually overflows it’s HTML container.

This is easy to reproduce;

  1. Write some text in an HtmlArea (preferably a narrow one)
  2. Edit some words so they are longer (i.e. test --> testetest).
  3. Save

The HtmlArea which previously might have looked like this:
<-Container->
test test test
test test test
test test

Now look like this (after editing the three first words):
<-Container->
testetest testetest testetest
test test test
test test


What it should be:
<-Container->
testetest
testetest
testetest
test test test
test test