Rails4: replace deprecated Relation#first with finder options at ChangesetTest

git-svn-id: http://svn.redmine.org/redmine/trunk@12538 e93f8b46-1217-0410-a6f0-8f06a7374b81
remove unneeded Relation#all from ChangesetTest#test_ref_keywords_closing_with_timelog

git-svn-id: http://svn.redmine.org/redmine/trunk@12539 e93f8b46-1217-0410-a6f0-8f06a7374b81