Reword some exception messages.

lib/Predis/Monitor/MonitorContext.php

@@ -53,7 +53,7 @@ class MonitorContext implements \Iterator
     private function checkCapabilities(ClientInterface $client)
     {
         if ($client->getConnection() instanceof AggregatedConnectionInterface) {
-            throw new NotSupportedException('Cannot initialize a monitor context over a cluster of connections');
+            throw new NotSupportedException('Cannot initialize a monitor context when using aggregated connections');
         }
 
         if ($client->getProfile()->supportsCommand('monitor') === false) {

lib/Predis/PubSub/PubSubContext.php

@@ -50,7 +50,7 @@ class PubSubContext extends AbstractPubSubContext
     private function checkCapabilities(ClientInterface $client)
     {
         if ($client->getConnection() instanceof AggregatedConnectionInterface) {
-            throw new NotSupportedException('Cannot initialize a PUB/SUB context over a cluster of connections');
+            throw new NotSupportedException('Cannot initialize a PUB/SUB context when using aggregated connections');
         }
 
         $commands = array('publish', 'subscribe', 'unsubscribe', 'psubscribe', 'punsubscribe');

lib/Predis/Transaction/MultiExecContext.php

@@ -118,7 +118,7 @@ class MultiExecContext implements BasicClientInterface, ExecutableContextInterfa
     private function checkCapabilities(ClientInterface $client)
     {
         if ($client->getConnection() instanceof AggregatedConnectionInterface) {
-            throw new NotSupportedException('Cannot initialize a MULTI/EXEC context over a cluster of connections');
+            throw new NotSupportedException('Cannot initialize a MULTI/EXEC context when using aggregated connections');
         }
 
         $profile = $client->getProfile();
@@ -440,8 +440,8 @@ class MultiExecContext implements BasicClientInterface, ExecutableContextInterfa
      */
     private function onProtocolError($message)
     {
-        // Since a MULTI/EXEC block cannot be initialized over a clustered
-        // connection, we can safely assume that Predis\Client::getConnection()
+        // Since a MULTI/EXEC block cannot be initialized when using aggregated
+        // connections, we can safely assume that Predis\Client::getConnection()
         // will always return an instance of Predis\Connection\SingleConnectionInterface.
         Helpers::onCommunicationException(new ProtocolException(
             $this->client->getConnection(), $message

tests/Predis/Monitor/MonitorContextTest.php

@@ -41,7 +41,7 @@ class MonitorContextTest extends StandardTestCase
     /**
      * @group disconnected
      * @expectedException Predis\NotSupportedException
-     * @expectedExceptionMessage Cannot initialize a monitor context over a cluster of connections
+     * @expectedExceptionMessage Cannot initialize a monitor context when using aggregated connections
      */
     public function testMonitorContextDoesNotWorkOnClusters()
     {

tests/Predis/PubSub/PubSubContextTest.php

@@ -40,7 +40,7 @@ class PubSubContextTest extends StandardTestCase
     /**
      * @group disconnected
      * @expectedException Predis\NotSupportedException
-     * @expectedExceptionMessage Cannot initialize a PUB/SUB context over a cluster of connections
+     * @expectedExceptionMessage Cannot initialize a PUB/SUB context when using aggregated connections
      */
     public function testPubSubContextDoesNotWorkOnClusters()
     {