conversation: fix bug related to use of shut down swarm manager

The SwarmManager class uses the 'isShutdown_' variable to keep track of
whether it has been shut down or not. This variable needs to be reset to
false if we want to restart using a SwarmManager after it was shut down,
which we sometimes do when bootstrapping a conversation.

This patch fixes a failure in
ConversationRequestTest::testBanContactRestartAccount that was
introduced by commit eb4213d3.
GitLab: #1002

Change-Id: If5d295cbae4edd9e2292d7464e2eb2939b05eedb

src/jamidht/conversation.cpp

@@ -2339,6 +2339,7 @@ Conversation::bootstrap(std::function<void()> onBootstraped,
     pimpl_->checkedMembers_.clear();
     // If is shutdown, the conversation was re-added, causing no new nodes to be connected, but just a classic connectivity change
     if (pimpl_->swarmManager_->isShutdown()) {
+        pimpl_->swarmManager_->restart();
         pimpl_->swarmManager_->maintainBuckets();
     } else if (!pimpl_->swarmManager_->setKnownNodes(devices)) {
         fallback(this, true);

src/jamidht/swarm/swarm_manager.cpp

@@ -146,6 +146,12 @@ SwarmManager::shutdown()
     routing_table.shutdownAllNodes();
 }
 
+void
+SwarmManager::restart()
+{
+    isShutdown_ = false;
+}
+
 bool
 SwarmManager::addKnownNode(const NodeId& nodeId)
 {

src/jamidht/swarm/swarm_manager.h

@@ -112,6 +112,14 @@ public:
      */
     void shutdown();
 
+    /**
+     * Restart the swarm manager.
+     *
+     * This function must be called in situations where we want
+     * to use a swarm manager that was previously shut down.
+     */
+    void restart();
+
     /**
      * Display swarm manager info
      */