Fixes #486 Update docs and fix failing test.

docs/CHANGES.md

 # Changelog
 
+## 2.0.6 (2017-02-01)
+- #486 Honor existing mam user configuration [throwaway42]
+
 ## 2.0.5 (2017-02-01)
 - #743, #751, #753 Update to Strophe 1.2.12. SASL-EXTERNAL now has reduced priority, so it won't
   be prioritized above other auth mechanisms. [jcbrand]

docs/source/configuration.rst

@@ -656,13 +656,17 @@ Similar to `default_domain`_ but no other domains are allowed.
 message_archiving
 -----------------
 
-* Default:  ``never``
+* Default:  ``undefined``
 
 Provides support for `XEP-0313: Message Archive Management <https://xmpp.org/extensions/xep-0313.html>`_,
-whereby messages are archived in the XMPP server for later retrieval. Note, your XMPP server must support
-XEP-0313 MAM for this to work.
+whereby messages are archived in the XMPP server for later retrieval.
+Note, your XMPP server must support XEP-0313 MAM for this to work.
+
+This option sets the default archiving preference.
+Valid values are ``undefined``, ``never``, ``always`` and ``roster``.
 
-This option sets the default archiving preference. Valid values are ``never``, ``always`` and ``roster``.
+``undefined`` means that any existing MAM configuration, as set by the user or
+the server administrator, will be used.
 
 ``roster`` means that only messages to and from JIDs in your roster will be
 archived. The other two values are self-explanatory.

spec/mam.js

@@ -387,6 +387,7 @@
                     IQ_id = sendIQ.bind(this)(iq, callback, errback);
                 });
                 spyOn(converse, 'onMAMPreferences').andCallThrough();
+                converse.message_archiving = 'never';
 
                 var feature = new converse.Feature({
                     'var': Strophe.NS.MAM
@@ -401,7 +402,6 @@
                     "</iq>"
                 );
 
-                converse.message_archiving = 'never';
                 /* Example 15. Server responds with current preferences
                  *
                  * <iq type='result' id='juliet2'>

src/converse-mam.js

@@ -282,7 +282,7 @@
                 var prefs = feature.get('preferences') || {};
                 if (feature.get('var') === Strophe.NS.MAM &&
                         prefs['default'] !== converse.message_archiving &&
-                        converse.message_archiving ) {
+                        !_.isUndefined(converse.message_archiving) ) {
                     // Ask the server for archiving preferences
                     converse.connection.sendIQ(
                         $iq({'type': 'get'}).c('prefs', {'xmlns': Strophe.NS.MAM}),