org-store-link: Return link when invoked from within agenda buffer

* org.el (org-store-link): Return link when invoked non-interactively from
an agenda buffer.

TINYCHANGE

> Summary:
>
> When I trigger a org-capture, with the cursor positioned on a line in
> the agenda buffer, I want the link to the agenda entry to be available
> as an annotation (%a) to the capture process. Currently this is broken.
>
> The enclosed patch fixes this.
>
> Setup:
>
> # file todo.org
> * TODO Talk to someone
>    SCHEDULED: <2010-08-23 Mon>
>
> # org-capture-templates
>  ("z" "Conversation" entry
>   (file+headline "~/conversation.org" "Conversations")
>   "** Note taken on %U\n   %a\n   %?" :prepend t :empty-lines 1)
>
> Steps for reporduction:
>
> 1. Restrict agenda to todo.org
> 2. Do org-agenda
> 3. Place the cursor on the above todo line
> 4. Trigger an org-capture for the above capture entry
>
> Examine the entries in conversation.org before/after the patch is
> applied. Note the absence/presence of the link to the parent todo entry.
>
> * Conversations
>
> ** Note taken on [2010-08-23 Mon 03:58]
>    [[file:~/todo.org::*Talk%20to%20someone][Talk to someone]]
>
> ** Note taken on [2010-08-23 Mon 03:42]
>
> Jambunathan K.

lisp/org.el

@@ -8218,7 +8218,7 @@ For file links, arg negates `org-context-in-file-links'."
   (org-load-modules-maybe)
   (setq org-store-link-plist nil)  ; reset
   (let ((outline-regexp (org-get-limited-outline-regexp))
-	link cpltxt desc description search txt custom-id)
+	link cpltxt desc description search txt custom-id agenda-link)
     (cond
 
      ((run-hook-with-args-until-success 'org-store-link-functions)
@@ -8250,9 +8250,10 @@ For file links, arg negates `org-context-in-file-links'."
 		   (get-text-property (point) 'org-marker))))
 	(when m
 	  (org-with-point-at m
-	    (if (interactive-p)
-		(call-interactively 'org-store-link)
-	      (org-store-link nil))))))
+	    (setq agenda-link
+		  (if (interactive-p)
+		      (call-interactively 'org-store-link)
+		    (org-store-link nil)))))))
 
      ((eq major-mode 'calendar-mode)
       (let ((cd (calendar-cursor-to-date)))
@@ -8392,7 +8393,7 @@ For file links, arg negates `org-context-in-file-links'."
 			       "::#" custom-id))
 	    (setq org-stored-links
 		  (cons (list link desc) org-stored-links))))
-      (and link (org-make-link-string link desc)))))
+      (or agenda-link (and link (org-make-link-string link desc))))))
 
 (defun org-store-link-props (&rest plist)
   "Store link properties, extract names and addresses."