[Backport] lisp/gnus/nnimap.el (nnimap-find-expired-articles): nnimap `never' expiration fix

lisp/gnus/ChangeLog

@@ -1,10 +1,15 @@
+2015-01-28  Elias Oltmanns  <eo@nebensachen.de>
+
+	* nnimap.el (nnimap-find-expired-articles): Fix handling of
+	(expiry-wait . never).
+
 2014-12-19  Andreas Schwab  <schwab@linux-m68k.org>
 
 	* gnus-group.el (gnus-read-ephemeral-bug-group): Bind
 	coding-system-for-read and coding-system-for-write only around
 	with-temp-file, and make buffer unibyte.  Don't write temp file twice.
 
-2014-11-26  John Mastro <john.b.mastro@gmail.com>  (tiny change)
+2014-11-26  John Mastro  <john.b.mastro@gmail.com>  (tiny change)
 
 	* auth-source.el (auth-source-macos-keychain-search-items): Return
 	result of `auth-source-macos-keychain-result-append' (bug#19074).

lisp/gnus/nnimap.el

@@ -979,19 +979,20 @@ textual parts.")
 
 (defun nnimap-find-expired-articles (group)
   (let ((cutoff (nnmail-expired-article-p group nil nil)))
-    (with-current-buffer (nnimap-buffer)
-      (let ((result
-	     (nnimap-command
-	      "UID SEARCH SENTBEFORE %s"
-	      (format-time-string
-	       (format "%%d-%s-%%Y"
-		       (upcase
-			(car (rassoc (nth 4 (decode-time cutoff))
-				     parse-time-months))))
-	       cutoff))))
-	(and (car result)
-	     (delete 0 (mapcar #'string-to-number
-			       (cdr (assoc "SEARCH" (cdr result))))))))))
+    (when cutoff
+      (with-current-buffer (nnimap-buffer)
+	(let ((result
+	       (nnimap-command
+		"UID SEARCH SENTBEFORE %s"
+		(format-time-string
+		 (format "%%d-%s-%%Y"
+			 (upcase
+			  (car (rassoc (nth 4 (decode-time cutoff))
+				       parse-time-months))))
+		 cutoff))))
+	  (and (car result)
+	       (delete 0 (mapcar #'string-to-number
+				 (cdr (assoc "SEARCH" (cdr result)))))))))))
 
 
 (defun nnimap-find-article-by-message-id (group server message-id