[gmime] Use the correct virtual write_to_stream() method for the body

[Jeffrey Stedfast <fejj src gnome org>]

commit 75f18ed1ebab398bc02cf6fe40941b1c8357f880
Author: Jeffrey Stedfast <jestedfa microsoft com>
Date:   Fri Feb 3 12:47:21 2017 -0500

    Use the correct virtual write_to_stream() method for the body

 gmime/gmime-message.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/gmime/gmime-message.c b/gmime/gmime-message.c
index e81ef63..b61852e 100644
--- a/gmime/gmime-message.c
+++ b/gmime/gmime-message.c
@@ -1091,6 +1091,7 @@ static ssize_t
 message_write_to_stream (GMimeObject *object, GMimeStream *stream, gboolean content_only)
 {
        GMimeMessage *message = (GMimeMessage *) object;
+       GMimeObject *mime_part = message->mime_part;
        ssize_t nwritten, total = 0;
        
        if (!content_only) {
@@ -1105,8 +1106,8 @@ message_write_to_stream (GMimeObject *object, GMimeStream *stream, gboolean cont
                total += nwritten;
        }
        
-       if (message->mime_part) {
-               if ((nwritten = GMIME_OBJECT_GET_CLASS (object)->write_to_stream (message->mime_part, stream, 
TRUE)) == -1)
+       if (mime_part) {
+               if ((nwritten = GMIME_OBJECT_GET_CLASS (mime_part)->write_to_stream (mime_part, stream, 
TRUE)) == -1)
                        return -1;
                
                total += nwritten;
@@ -1553,7 +1554,7 @@ g_mime_message_get_mime_part (GMimeMessage *message)
 void
 g_mime_message_set_mime_part (GMimeMessage *message, GMimeObject *mime_part)
 {
-       g_return_if_fail (mime_part == NULL || GMIME_IS_OBJECT (mime_part));
+       g_return_if_fail (GMIME_IS_OBJECT (mime_part));
        g_return_if_fail (GMIME_IS_MESSAGE (message));
        
        if (message->mime_part == mime_part)