Update log message from EC2 RunInstances call to include number of no…

…des requested (#1033)

* Log EC2 errors while calling RunInstances for reserved capacity

* Update log message to include number of nodes requested

src/main/java/hudson/plugins/ec2/SlaveTemplate.java

@@ -2032,7 +2032,9 @@ private List<EC2AbstractSlave> provisionOndemand(
             try {
                 newInstances = ec2.runInstances(riRequest).getReservation().getInstances();
             } catch (AmazonEC2Exception e) {
-                logProvisionInfo("Error while trying to run instances for reserved capacity: " + e.getMessage());
+                logProvisionInfo("Jenkins attempted to reserve "
+                        + riRequest.getMaxCount()
+                        + " instances and received this EC2 exception: " + e.getMessage());
                 throw e;
             }
         }