Browser cache is not invalidated for attachment retrieved in another nested space

XWIKI-15450 was supposed to fix cache issue for all attachment but it appears that I make a mistake when retrieving document from another nested space.
Steps to reproduce:

• Create a space Foo and a nested space Bar
• Attach a picture in Foo.Bar.WebHome
• Display this picture in a document outside Foo.Bar space.

Expected result:

• The produced URL is protected against cache issue

Obtained result:

• the produce URL is a standard download one, that we got before XWIKI-15450.