Lock CommandQueueManager.PushMany too

src/NzbDrone.Core/Messaging/Commands/CommandQueueManager.cs

@@ -54,12 +54,14 @@ namespace NzbDrone.Core.Messaging.Commands
         {
             _logger.Trace("Publishing {0} commands", commands.Count);
 
+            lock (_commandQueue)
+            {
                 var commandModels = new List<CommandModel>();
                 var existingCommands = _commandQueue.QueuedOrStarted();
 
                 foreach (var command in commands)
                 {
-                var existing = existingCommands.SingleOrDefault(c => c.Name == command.Name && CommandEqualityComparer.Instance.Equals(c.Body, command));
+                    var existing = existingCommands.FirstOrDefault(c => c.Name == command.Name && CommandEqualityComparer.Instance.Equals(c.Body, command));
 
                     if (existing != null)
                     {
@@ -88,6 +90,7 @@ namespace NzbDrone.Core.Messaging.Commands
 
                 return commandModels;
             }
+        }
 
         public CommandModel Push<TCommand>(TCommand command, CommandPriority priority = CommandPriority.Normal, CommandTrigger trigger = CommandTrigger.Unspecified) where TCommand : Command
         {