fix source indent of Redmine::Scm::Adapters::AbstractAdapter#without_trailling_slash

git-svn-id: http://svn.redmine.org/redmine/trunk@12741 e93f8b46-1217-0410-a6f0-8f06a7374b81
Merge pull request #865 from marutosi/finn-abst-scm

fix source indent of Redmine::Scm::Adapters::AbstractAdapter#without_trailling_slash