add more error message if public/plugin_assets cannot be created (#11945)

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@10472 e93f8b46-1217-0410-a6f0-8f06a7374b81

lib/redmine/plugin.rb

@@ -336,7 +336,11 @@ module Redmine #:nodoc:
 
       unless source_files.empty?
         base_target_dir = File.join(destination, File.dirname(source_files.first).gsub(source, ''))
+        begin
           FileUtils.mkdir_p(base_target_dir)
+        rescue Exception => e
+          raise "Could not create directory #{base_target_dir}: " + e.message
+        end
       end
 
       source_dirs.each do |dir|