Gnus: Fix edge cases with no data being returned and Courier eccentricity.

* lisp/gnus/nnimap.el (nnimap-retrieve-headers-progress): Handle edge
  case where `headers' is nil.  This can occur if the IMAP server does
  not have permissions to read messages from a folder, but can write new
  messages to the folder.
  (nnimap-request-article-part): Do not insert `data' if it is nil.

* lisp/net/imap.el (imap-parse-fetch): Courier can insert spurious blank
  characters which will confuse `read', so skip past them.

1 files changed, 3 insertions, 1 deletions

diff --git a/lisp/net/imap.el b/lisp/net/imap.el
index 6726bfda200..85afffc100b 100644
--- a/lisp/net/imap.el
+++ b/lisp/net/imap.el
@@ -2493,7 +2493,9 @@ Return nil if no complete line has arrived."
   (when (eq (char-after) ?\()
     (let (uid flags envelope internaldate rfc822 rfc822header rfc822text
               rfc822size body bodydetail bodystructure flags-empty)
-      (while (not (eq (char-after) ?\)))
+      (while (let ((moved (skip-chars-forward " \t")))
+               (prog1 (not (eq (char-after) ?\)))
+                 (unless (= moved 0) (backward-char))))
         (imap-forward)
         (let ((token (read (current-buffer))))
           (imap-forward)