Debugging files with same name?

Environment is openSuse12.1 and ruby 1.8.7

I just tried to debug a project with several files of the same filename
in different subdirectories (see attachment) and the debugger
(ruby-debug) is not giving me the path in back-traces even if I did “set
fullpath”. It even shows the wrong source code upon breakpoint hit in
one of the files with the same name:

I debug subscript from subfolder and do

b ./req_base.rb:2

then it tells me that it will break at:

Breakpoint 1 at /same_files/subfolder/req_base.rb:2

and then, when I continue it actually breaks in
subsubfolder/req_base.rb:2 and shows the source that is in there.
“where” does not show the full path of req_base.rb.

Is this expected behaviour (am I doing wrong with same filenames) or
just a plain bug?