Error on 2.4.1

[sosyco]

on Installation the plugin on 2.4.1 wie see the following errors.

a) wrong installation instructions for getting the plugin:
git clone git@github.com:IceskYsl/holidays.git
we used: git clone git://github.com/IceskYsl/holidays.git

b) errors on migrate to redmine:
rake redmine:plugins:migrate RAILS_ENV=production
...
rake aborted!
/var/lib/gems/1.9.1/gems/rake-10.1.0/lib/rake/trace_output.rb:16:in block in trace_on': invalid byte sequence in US-ASCII (ArgumentError) from /var/lib/gems/1.9.1/gems/rake-10.1.0/lib/rake/trace_output.rb:14:inmap'
from /var/lib/gems/1.9.1/gems/rake-10.1.0/lib/rake/trace_output.rb:14:in trace_on' from /var/lib/gems/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:340:intrace'
from /var/lib/gems/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:187:in display_error_message' from /var/lib/gems/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:174:inrescue in standard_exception_handling'
from /var/lib/gems/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:165:in standard_exception_handling' from /var/lib/gems/1.9.1/gems/rake-10.1.0/lib/rake/application.rb:75:inrun'
from /var/lib/gems/1.9.1/gems/rake-10.1.0/bin/rake:33:in <top (required)>' from /usr/local/bin/rake:23:inload'
from /usr/local/bin/rake:23:in `

'
...

no problems with other plugins.
we use redmine 2.4.1 on debian wheezy with german utf8 localization