Path Inconsistency when Operating statCache within Yarn Client

The addResource from ClientDistributedCacheManager can add FileStatus to 

statCache when it is not yet cached. Also, there is a subtle bug from isPublic from 

getVisibility method. uri.getPath() will not retain URI information like 

scheme, host, etc. So, the uri passed to checkPermissionOfOther will differ from the original uri.

For example, if uri is "file:/foo.invalid.com:8080/tmp/testing", then 

uri.getPath -> /foo.invalid.com:8080/tmp/testing
uri.toString -> file:/foo.invalid.com:8080/tmp/testing

The consequence of this bug is that we will double RPC calls when the resources are remote, which is unnecessary. We see nontrivial overhead when checking those resources from our HDFS, especially when HDFS is overloaded. 

Ref: related code within ClientDistributedCacheManager

def addResource(...) {
    val destStatus = statCache.getOrElse(destPath.toUri(), fs.getFileStatus(destPath))
val visibility = getVisibility(conf, destPath.toUri(), statCache)
}
private[yarn] def getVisibility() {
isPublic(conf, uri, statCache)
}
private def isPublic(conf: Configuration, uri: URI, statCache: Map[URI, FileStatus]): Boolean = {
val current = new Path(uri.getPath()) // Should not use getPath
checkPermissionOfOther(fs, uri, FsAction.READ, statCache)
}