Per HDFS-3318 the content length header check breaks distcp compatibility with previous releases (0.20.2 and earlier, and 0.21). Like branch-1 this check should be lenient.
WebHdfsFileSystem can not read files larger than 24KB
Create files with WebHdfsFileSystem goes OOM when file size is big
distcp can't copy large files using webhdfs due to missing Content-Length header
Hftp hangs on transfers >2GB