[MCL-1536] 1.6.4 Download Errors

Basically, I opened the launcher and noticed the new release. I clicked "log in" and the download began the same as usual. Then the launcher said there was the following error:

Fatal error launching game. Report this to http://mojang.atlassian.net please!
java.lang.NoClassDefFoundError: org/apache/commons/io/filefilter/AgeFileFilter
	at net.minecraft.launcher.GameLauncher.cleanOldNatives(GameLauncher.java:342)
	at net.minecraft.launcher.GameLauncher.launchGame(GameLauncher.java:190)
	at net.minecraft.launcher.GameLauncher.onDownloadJobFinished(GameLauncher.java:512)
	at net.minecraft.launcher.updater.download.DownloadJob.startDownloading(DownloadJob.java:75)
	at net.minecraft.launcher.Launcher$1.run(Launcher.java:157)
	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
	at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
	at java.util.concurrent.FutureTask.run(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.io.filefilter.AgeFileFilter
	at java.net.URLClassLoader$1.run(Unknown Source)
	at java.net.URLClassLoader$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	... 11 more

Please look into this! thanks