bug#3875: 23.1.50; buffer-substring does not copy the 'invisible property

A simple test in for example an org-mode buffer shows this. The doc
string says it should copy the properties.

How do I get a buffer substring with the text property 'invisible too?
Do I have to search them in the buffer and apply them to the string?
In that case should not Emacs have a function to do this?


In GNU Emacs 23.1.50.1 (i386-mingw-nt5.1.2600)
 of 2009-06-30
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --no-opt --cflags
-Ic:/g/include -fno-crossjumping'