webapp: rake assets:precompile: can't convert nil into Hash

--- git/bitmask ‹develop› » leap deploy web1     
 = checking node
   - [web1] ok
 = synching configuration files
   - hiera/web1.yaml -> web1:/etc/leap/hiera.yaml
   - files/ca/client_ca.crt, files/ca/client_ca.key, files/branding/favicon.ico, files/branding/tail.scss, files/branding/head.scss -> web1:/etc/leap
 = synching puppet manifests
   - /home/varac/dev/projects/leap/git/leap_platform/[bin,puppet] -> web1:/srv/leap
 = applying puppet
   - [web1] notice: Scope(Class[main]): Services for web1.bitmask.net: webapp
   - [web1] notice: /Stage[main]/Site_webapp/Vcsrepo[/srv/leap/webapp]/revision: revision changed 'cc32ad53286c2c03c88cb55713565c2930796024' to 'origin/master'
   - [web1] notice: /Stage[main]/Site_webapp/Exec[bundler_update]: Triggered 'refresh' from 1 events
   - [web1] err: /Stage[main]/Site_webapp/Exec[compile_assets]/returns: change from notrun to 0 failed: /bin/bash -c "/usr/bin/bundle exec rake assets:precompile" returned 1 instead of one of [0] at /srv/leap/puppet/modules/site_webapp/manifests/init.pp:69
   - [web1] notice: /Stage[main]/Resolvconf/File[/etc/resolv.conf]/content: content changed '{md5}2a8dd35b454f121e0cd5a7776be2837a' to '{md5}7ad39c9811b952ca2d29385eff848d44'
   - [web1] notice: /Stage[main]/Apache::Base/Service[apache]: Dependency Exec[compile_assets] has failures: true
   - [web1] warning: /Stage[main]/Apache::Base/Service[apache]: Skipping because of failed dependencies
   - [web1] notice: /Stage[main]/Apache::Base/Service[apache]: Triggered 'refresh' from 2 events
   - [web1] notice: /Stage[main]/Site_nickserver/File[/etc/leap/nickserver.yml]/ensure: defined content as '{md5}69ce8c2492496c85dc6066855bd22d1d'
   - [web1] err: /Stage[main]/Site_nickserver/Service[nickserver]: Failed to call refresh: Could not restart Service[nickserver]: Execution of '/etc/init.d/nickserver restart' returned 1:  at /srv/leap/puppet/modules/site_nickserver/manifests/init.pp:126
   - [web1] notice: Finished catalog run in 36.33 seconds
   - [web1] Puppet apply complete (changes and failures).

root@web1:/srv/leap/webapp# /bin/bash -c "/usr/bin/bundle exec rake assets:precompile"
rake aborted!
can't convert nil into Hash
/srv/leap/webapp/config/application.rb:20:in `merge'
/srv/leap/webapp/config/application.rb:20:in `block in '
/srv/leap/webapp/config/application.rb:18:in `each'
/srv/leap/webapp/config/application.rb:18:in `inject'
/srv/leap/webapp/config/application.rb:18:in `'
/srv/leap/webapp/Rakefile:13:in `require'
/srv/leap/webapp/Rakefile:13:in `'
(See full trace by running task with --trace)

(from redmine: created on 2013-07-16, closed on 2013-07-17, relates #3156 (closed), relates #3226 (closed), relates #3382 (closed))