Merged r13198 from trunk to 2.5-stable (#17235)

Prevent "can't modify frozen String" exception when mail sending error.

git-svn-id: http://svn.redmine.org/redmine/branches/2.5-stable@13200 e93f8b46-1217-0410-a6f0-8f06a7374b81
Merged r13199 from trunk to 2.5-stable (#17151)

Fix file upload broken on Chrome 36.

Contributed by Felix Schäfer.

git-svn-id: http://svn.redmine.org/redmine/branches/2.5-stable@13201 e93f8b46-1217-0410-a6f0-8f06a7374b81