Exporting to RSS (using say, org-export-to-buffer) fails when the org
buffer has no filename. If the same contents are saved to a file on
disk, then exporting works normally.

Is this expected and normal behaviour? Or can it be considered a bug?

Please find attached a tarball with the backtrace of the error, and a
minimal init file to reproduce the bug. To reproduce the bug, just
extract the tarball, and run

emacs -Q -l minimal-org.el

Thanks,
Arun Isaac.

Emacs  : GNU Emacs 24.5.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.16.6)
 of 2015-09-10 on foutrelis
Package: Org-mode version 8.3.1 (release_8.3.1-495-gbd7908)