A new 0.2.5 version has been released that fixes some issues reported
by Armin.  You can get it by running:

sudo easy_install -U rosrelease

NOTE: rosrelease-legacy is based on rosdep 2.  rosdep 2 *does not*
read <stack>/rosdep.yaml.  Instead, it refers to "sources" in
/etc/ros/rosdep/sources.list.d to lookup keys.   The current sources
should include most of the existing rosdep rules; they are now just
organized into 2 main files, plus a separate OS X Homebrew file.

The new rosdep 2 architecture is meant to make releases much easier:
no more re-releases in order to update rosdep rules, no more difficult
conflict resolution between different stacks, easier to roll out
updates for new Ubuntu releases, one location/repo to store rules,
etc...

Documentation on contributing new rosdep rules:

http://ros.org/doc/api/rosdep2/html/contributing_rules.html

 - Ken