[Patch] don't add indent for empty line when exiting, a code edit

[Arun Persaud <apersaud@lbl.gov>]

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Hi

I started using org babel for python, but when using C-c ' I always
ended up with white space added to the empty lines in the source code
when returning into the org buffer. This especially shows up
(setq-default show-trailing-whitespace t).

I tried to fix this in org. It seems to work over here, but my elisp as
well as my understanding of org-mode is not perfect ;) Let me know if it
needs more work.

Arun

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From e393fed9dbb132fdefff66d304f67f7def643140 Mon Sep 17 00:00:00 2001
From: Arun Persaud <arun@nubati.net>
Date: Mon, 10 Mar 2014 17:09:12 -0700
Subject: [PATCH] lisp/org-src.el: don't add indent for empty line when exiting
 a code edit

Using C-c ' to edit code blocks adds an indent to all lines when exiting from
the code edit. This leaves trailing whitespace in the buffer, which can be especially
annoying when using show-trailing-whitespace.
---
 lisp/org-src.el | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lisp/org-src.el b/lisp/org-src.el
index d1f6879..ef09bd6 100644
--- a/lisp/org-src.el
+++ b/lisp/org-src.el
@@ -737,8 +737,10 @@ with \",*\", \",#+\", \",,*\" and \",,#+\"."
       (unless (or single preserve-indentation (= total-nindent 0))
 	(setq indent (make-string total-nindent ?\ ))
 	(goto-char (point-min))
-	(while (re-search-forward "^" nil t)
-	  (replace-match indent)))
+        (while (re-search-forward "^" nil t)
+          (if (not (looking-at "$"))
+              (replace-match indent)
+	    (forward-char 1))))
       (if (org-bound-and-true-p org-edit-src-picture)
 	  (setq total-nindent (+ total-nindent 2)))
       (setq code (buffer-string))
-- 
1.9.0