php composer.phar require "ezsystems/ezpublish-community"                                                    
Please provide a version constraint for the ezsystems/ezpublish-community requirement: v5.3.0-rc4
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for ezsystems/ezpublish-community v5.3.0-rc4 -> satisfiable by ezsystems/ezpublish-community[v5.3.0-rc4].
    - ezsystems/ezpublish-community v5.3.0-rc4 requires ezsystems/demobundle 5.3.*@rc -> no matching package found.

Potential causes:
 - A typo in the package name
 - The package is not available in a stable-enough version according to your minimum-stability setting
   see <https://groups.google.com/d/topic/composer-dev/_g3ASeIFlrc/discussion> for more details.

Read <http://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.

Installation failed, reverting ./composer.json to its original content.