Don't link multiple changesets from the same commit multiple times (#17931).

git-svn-id: http://svn.redmine.org/redmine@13427 e93f8b46-1217-0410-a6f0-8f06a7374b81
Fixed that preview doesn't show notes when issue project is changed (#17959).

git-svn-id: http://svn.redmine.org/redmine@13428 e93f8b46-1217-0410-a6f0-8f06a7374b81
Reverts change in r13428, project can't be found by identifier (#17959).

git-svn-id: http://svn.redmine.org/redmine@13429 e93f8b46-1217-0410-a6f0-8f06a7374b81