Fixed #27848 -- Prevented crash when attaching a .eml file to a message

Thanks Sébastien Ramage for the report.

django/core/mail/message.py

@@ -381,7 +381,7 @@ class EmailMessage:
             elif not isinstance(content, Message):
                 # For compatibility with existing code, parse the message
                 # into an email.Message object if it is not one already.
-                content = message_from_string(content)
+                content = message_from_string(force_text(content))
 
             attachment = SafeMIMEMessage(content, subtype)
         else:

tests/mail/attachments/file.eml

@@ -0,0 +1,44 @@
+MIME-Version: 1.0
+Received: by 10.220.191.194 with HTTP; Wed, 11 May 2011 12:27:12 -0700 (PDT)
+Date: Wed, 11 May 2011 13:27:12 -0600
+Delivered-To: jncjkq@gmail.com
+Message-ID: <BANLkTi=JCQO1h3ET-pT_PLEHejhSSYxTZw@mail.jncjkq.com>
+Subject: Test
+From: Bill Jncjkq <jncjkq@gmail.com>
+To: bookmarks@jncjkq.net
+Content-Type: multipart/mixed; boundary=bcaec54eecc63acce904a3050f79
+
+--bcaec54eecc63acce904a3050f79
+Content-Type: multipart/alternative; boundary=bcaec54eecc63acce604a3050f77
+
+--bcaec54eecc63acce604a3050f77
+Content-Type: text/plain; charset=ISO-8859-1
+
+--
+Bill Jncjkq
+
+--bcaec54eecc63acce604a3050f77
+Content-Type: text/html; charset=ISO-8859-1
+
+<br clear="all">--<br>Bill Jncjkq<br>
+
+--bcaec54eecc63acce604a3050f77--
+--bcaec54eecc63acce904a3050f79
+Content-Type: text/html; charset=US-ASCII; name="bookmarks-really-short.html"
+Content-Disposition: attachment; filename="bookmarks-really-short.html"
+Content-Transfer-Encoding: base64
+X-Attachment-Id: f_gnknv6u70
+
+PCFET0NUWVBFIE5FVFNDQVBFLUJvb2ttYXJrLWZpbGUtMT4KCTxIVE1MPgoJPE1FVEEgSFRUUC1F
+UVVJVj0iQ29udGVudC1UeXBlIiBDT05URU5UPSJ0ZXh0L2h0bWw7IGNoYXJzZXQ9VVRGLTgiPgoJ
+PFRpdGxlPkJvb2ttYXJrczwvVGl0bGU+Cgk8SDE+Qm9va21hcmtzPC9IMT4KCQk8RFQ+PEgzIEZP
+TERFRD5UZWNoIE5ld3M8L0gzPgoJCTxETD48cD4KCQkJPERUPjxBIEhSRUY9Imh0dHA6Ly93d3cu
+Y25ldC5jb20vIj5DTmV0PC9BPgoJCQk8RFQ+PEEgSFJFRj0iaHR0cDovL3d3dy53aXJlZC5jb20v
+Ij5XaXJlZCBOZXdzPC9BPgoJCTwvREw+PHA+CgkJPERUPjxIMyBGT0xERUQ+VG9vbHMgYW5kIFJl
+ZmVyZW5jZTwvSDM+CgkJPERMPjxwPgoJCQk8RFQ+PEEgSFJFRj0iaHR0cDovL3d3dy5tb25zdGVy
+LmNvbS8iPk1vbnN0ZXIuY29tPC9BPgoJCQk8RFQ+PEEgSFJFRj0iaHR0cDovL3d3dy53ZWJtZC5j
+b20vIj5XZWJNRDwvQT4KCQk8L0RMPjxwPgoJCTxEVD48SDMgRk9MREVEPlRyYXZlbDwvSDM+CgkJ
+PERMPjxwPgoJCQk8RFQ+PEEgSFJFRj0iaHR0cDovL2ZvZG9ycy5jb20vIj5Gb2RvcnM8L0E+CgkJ
+CTxEVD48QSBIUkVGPSJodHRwOi8vd3d3LnRyYXZlbG9jaXR5LmNvbS8iPlRyYXZlbG9jaXR5PC9B
+PgoJCTwvREw+PHA+Cgk8L0RMPjxwPgo8L0hUTUw+
+--bcaec54eecc63acce904a3050f79--

tests/mail/tests.py

@@ -401,6 +401,7 @@ class MailTests(HeadersCheckMixin, SimpleTestCase):
             ('file_png', None),
             ('file_txt.png', 'image/png'),
             ('file_png.txt', 'text/plain'),
+            ('file.eml', 'message/rfc822'),
         )
         test_mimetypes = ['text/plain', 'image/png', None]