Only fetch presences when we're resuming an existing session.

updates #555

src/headless/converse-bosh.js

@@ -87,7 +87,6 @@ converse.plugins.add('converse-bosh', {
                     _converse.log(
                         "Could not restore session for jid: "+
                         jid+" Error message: "+e.message, Strophe.LogLevel.WARN);
-                    _converse.clearSession(); // We want to clear presences (see #555)
                     return false;
                 }
             }

src/headless/converse-core.js

@@ -323,6 +323,16 @@ function isTestEnv () {
 }
 
 
+_converse.haveResumed = function () {
+    if (_converse.api.connection.isType('bosh')) {
+        return _converse.connfeedback.get('connection_status') === Strophe.Status.ATTACHED;
+    } else {
+        // XXX: Not binding means that the session was resumed.
+        // This seems very fragile. Perhaps a better way is possible.
+        return !_converse.connection.do_bind;
+    }
+}
+
 _converse.isUniView = function () {
     /* We distinguish between UniView and MultiView instances.
      *

src/headless/converse-roster.js

@@ -965,7 +965,12 @@ converse.plugins.add('converse-roster', {
             }
             _converse.presences.browserStorage =
                 new BrowserStorage.session(`converse.presences-${_converse.bare_jid}`);
+
+            if (_converse.haveResumed()) {
                 _converse.presences.fetch();
+            } else {
+                _converse.presences.browserStorage._clear();
+            }
             /**
              * Triggered once the _converse.Presences collection has been
              * initialized and its cached data fetched.