fixed #734. Don't allow # of executors to be 0.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@6782 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/model/Slave.java

@@ -103,6 +103,9 @@ public final class Slave implements Node, Serializable {
         //    throw new FormException("Invalid slave configuration for " + name + ". No such directory exists: " + localFS, null);
         if (remoteFS.equals(""))
             throw new FormException("Invalid slave configuration for " + name + ". No remote directory given", null);
+
+        if (numExecutors<=0)
+            throw new FormException("Invalid slave configuration for " + name + ". Invalid # of executors.", null);
     }
 
     public String getCommand() {