merge after 3.4.3 release

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@21704 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
4687: global name 'warn' is not defined

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@21706 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
4687: missing content migration...

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@21711 4ae1f11a-8b86-4847-b8af-ab372f36d1fd