Don't embed CRLF multiple times when saving a message

Since we just do multiple passes for saving the message without
actually modifying its content (apart from header insertion that
is CRLF-clean), we can change line ends to the proper CRLF just
once.

And we can also get message's date only once too.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>

offlineimap/folder/IMAP.py

@@ -509,6 +509,12 @@ class IMAPFolder(BaseFolder):
             self.savemessageflags(uid, flags)
             return uid
 
+        # Use proper CRLF all over the message
+        content = re.sub("(?<!\r)\n", "\r\n", content)
+
+        # get the date of the message, so we can pass it to the server.
+        date = self.__getmessageinternaldate(content, rtime)
+
         retry_left = 2 # succeeded in APPENDING?
         imapobj = self.imapserver.acquireconnection()
         # NB: in the finally clause for this try we will release
@@ -521,10 +527,6 @@ class IMAPFolder(BaseFolder):
                 # UIDPLUS extension provides us with an APPENDUID response.
                 use_uidplus = 'UIDPLUS' in imapobj.capabilities
 
-                # get the date of the message, so we can pass it to the server.
-                date = self.__getmessageinternaldate(content, rtime)
-                content = re.sub("(?<!\r)\n", "\r\n", content)
-
                 if not use_uidplus:
                     # insert a random unique header that we can fetch later
                     (headername, headervalue) = self.__generate_randomheader(