How to insert a relative file name in calc

I’m trying to insert a relative file name in calc (on Fedora Linux), like:

='./test1.ods'#$sheet1.B2

however, this is automatically replaced by:

='file:///home/jan/tmp/test/test1.ods'#$Sheet1.B2

even though I have in Tools|Options…|Load/Save|General the following selected:

Save URLs relative to file system

Any suggestions on how to use relative URLs as references?

They’re always displayed as absolute URLs. The option for Save is something different, it determines whether the URL can be rewritten/built relative to a new location the document is loaded from.