Redmine

When opening a new issue and changing trackers, the icon to select dates from a calendar disappears.

```
Environment:
Redmine version 2.5.2.stable
Ruby version 1.9.3-p547 (2014-05-14) [amd64-freebsd9]
Rails version 3.2.19
Environment production
Database adapter Mysql2
SCM:
Subversion 1.8.11
Git 2.4.0
Filesystem
Redmine plugins:
a_common_libs 2.1.8
redmine_default_assign 0.4
redmine_graphs 0.1.0
redmine_ical thegcat-trunk
redmine_knowledgebase 2.3.0
redmine_ldap_sync 2.0.7
redmine_qa_contact 0.0.2
redmine_redcarpet_formatter 2.0.1
redmine_wiki_notes 0.0.1
single_auth 2.0.0
stuff_to_do_plugin 0.4.1
```