ediff-regions-internal can't handle (non-overlapping) regions in the same buffer

[Kevin Rodgers <ihs_4664@yahoo.com>]

I'm working on a way to take advantage of Ediff's fine highlighting
feature within Diff mode buffers.  But calling ediff-regions-internal
programmatically with BUFFER-A the same as BUFFER-B doesn't work,
leaving only the region between BEG-B and END-B highighted.  This is
because ediff-extract-diffs first resets point in both buffers (changing
point in BUFFER-A unintentionally), then builds the diff vector by
moving by lines in each buffer.

The fix is simple, and it allows ediff-regions-internal to work with
non-overlapping regions in the same buffer: Don't set point in each
buffer until necessary:

*** emacs-21.4/lisp/ediff-diff.el~	Wed Jul  3 10:49:40 2002
--- emacs-21.4/lisp/ediff-diff.el	Wed Dec  7 13:34:26 2005
***************
*** 378,388 ****
   	      (ediff-overlay-start
   	       (ediff-get-value-according-to-buffer-type 'B bounds))))

!     ;; reset point in buffers A/B/C
!     (ediff-with-current-buffer A-buffer
!       (goto-char (if shift-A shift-A (point-min))))
!     (ediff-with-current-buffer B-buffer
!       (goto-char (if shift-B shift-B (point-min))))
       (if (ediff-buffer-live-p C-buffer)
   	(ediff-with-current-buffer C-buffer
   	  (goto-char (point-min))))
--- 378,384 ----
   	      (ediff-overlay-start
   	       (ediff-get-value-according-to-buffer-type 'B bounds))))

!     ;; reset point in buffer C
       (if (ediff-buffer-live-p C-buffer)
   	(ediff-with-current-buffer C-buffer
   	  (goto-char (point-min))))
***************
*** 456,461 ****
--- 452,458 ----
   		   c-prev c-end)
   	   ;; else convert lines to points
   	   (ediff-with-current-buffer A-buffer
+              (goto-char (if shift-A shift-A (point-min)))
   	     (forward-line (- a-begin a-prev))
   	     (setq a-begin-pt (point))
   	     (forward-line (- a-end a-begin))
***************
*** 462,467 ****
--- 459,465 ----
   	     (setq a-end-pt (point)
   		   a-prev a-end))
   	   (ediff-with-current-buffer B-buffer
+              (goto-char (if shift-B shift-B (point-min)))
   	     (forward-line (- b-begin b-prev))
   	     (setq b-begin-pt (point))
   	     (forward-line (- b-end b-begin))

Thanks,
-- 
Kevin