Non breaking space inserted in numbered headings instead of normal space in PDF

Apparently since the 22nd of April the PDFExportIT#numberedHeadings test is failing on stable-16.10.x branch, because of non breaking spaces between the number and the title:
apparently the test is expecting a normal space and we obtain a non breaking like this:
> 1.1.1nbspHeading 1-1-1

It feels like it could be related to the upgrades we recently performed on that branch in xwiki-commons the 22nd.