Public plugin_assets path is not writeable after installation

[Mikkel Kirkgaard Nielsen]

On Ubuntu 16.04 after installing the Redmine project management system in package "redmine" the path for exposing plugins' assets to the web (/usr/share/redmine/public/plugin_assets/) is not writable as required by Redmine and causes a warning in the administration interface on /admin/info (code that performs this check at app/controllers/admin_controller.rb line 79).

The path needs to be writeable as plugin assets are copied here from plugins/<plugin name>/assets by the webserver dynamically (see code around /usr/share/redmine/lib/redmine/plugin.rb line 381).

The workaround is doing;
sudo chown www-data:www-data /usr/share/redmine/public/plugin_assets/ -R

See also the stale Debian bug; https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=684083

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.2 LTS
Release: 16.04
Codename: xenial

$ apt-cache policy redmine
redmine:
  Installed: 3.2.1-2
  Candidate: 3.2.1-2
  Version table:
 *** 3.2.1-2 500
        500 http://dk.archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
        500 http://dk.archive.ubuntu.com/ubuntu xenial/universe i386 Packages
        100 /var/lib/dpkg/status