Failed ES 1.4.0 Beta 1 plugin installation

gistfile1.txt

bin/plugin --install elasticsearch/elasticsearch-lang-mvel/2.0.0
-> Installing elasticsearch/elasticsearch-lang-mvel/2.0.0...
Trying http://download.elasticsearch.org/elasticsearch/elasticsearch-lang-mvel/elasticsearch-lang-mvel-2.0.0.zip...
Trying http://search.maven.org/remotecontent?filepath=elasticsearch/elasticsearch-lang-mvel/2.0.0/elasticsearch-lang-mvel-2.0.0.zip...
Trying https://oss.sonatype.org/service/local/repositories/releases/content/elasticsearch/elasticsearch-lang-mvel/2.0.0/elasticsearch-lang-mvel-2.0.0.zip...
Trying https://github.com/elasticsearch/elasticsearch-lang-mvel/archive/2.0.0.zip...
Trying https://github.com/elasticsearch/elasticsearch-lang-mvel/archive/master.zip...
Downloading ...........................DONE
Installed elasticsearch/elasticsearch-lang-mvel/2.0.0 into /usr/share/elasticsearch/plugins/lang-mvel
Usage:
    -u, --url     [plugin location]   : Set exact URL to download the plugin from
    -i, --install [plugin name]       : Downloads and installs listed plugins [*]
    -t, --timeout [duration]          : Timeout setting: 30s, 1m, 1h... (infinite by default)
    -r, --remove  [plugin name]       : Removes listed plugins
    -l, --list                        : List installed plugins
    -v, --verbose                     : Prints verbose messages
    -s, --silent                      : Run in silent mode
    -h, --help                        : Prints this help message

 [*] Plugin name could be:
     elasticsearch/plugin/version for official elasticsearch plugins (download from download.elasticsearch.org)
     groupId/artifactId/version   for community plugins (download from maven central or oss sonatype)
     username/repository          for site plugins (download from github master)

Message:
   Error while installing plugin, reason: IllegalArgumentException: Plugin installation assumed to be site plugin, but contains source code, aborting installation.