[O] bug / regression: C-x C-s is broken in org-edit-special

[Leo Alekseyev]

Previously, C-x C-s in an org-edit-special buffer (invoked via C-')
would save the underlying org buffer (provided (setq
org-src-window-setup (quote current-window)) was set; it was buggy
with other settings, see
http://thread.gmane.org/gmane.emacs.orgmode/50979 for discussion).
Currently, C-x C-s prompts to save the temporary source edit buffer in
a new file, which is almost certainly not what the user intends.  I
hope someone can look into this, C-x C-s shouldn't be broken in any
context.

This broke some time between commit
fc93b6f34071703d5a154a51540f3f4e3f15b8a2 (Jan. 18) and this week,
_possibly_ as a result of the change ensuring that buffer-file-name is
nil in temporary org-src buffers.  Buffer-file-name not being nil in a
temp buffer is incorrect behavior, but in this context having C-x C-s
not working is a much worse behavior, so perhaps that change ought to
be reverted if it's the culprit.

--Leo