messagesadapter: clear cached convId when existing message web view

Change-Id: I332bebfbd035f6c928a7a8f1d4210ce8b491c7dd

src/messagesadapter.cpp

@@ -489,6 +489,8 @@ MessagesAdapter::newInteraction(const QString& accountId,
 void
 MessagesAdapter::updateDraft()
 {
+    currentConvUid_.clear();
+
     Utils::oneShotConnect(qmlObj_,
                           SIGNAL(sendMessageContentSaved(const QString&)),
                           this,