Fix RuboCop offense Lint/NonAtomicFileOperation (#36919).

git-svn-id: https://svn.redmine.org/redmine/trunk@21694 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/models/attachment.rb

@@ -525,9 +525,7 @@ class Attachment < ActiveRecord::Base
 
   # Physically deletes the file from the file system
   def delete_from_disk!
-    if disk_filename.present? && File.exist?(diskfile)
-      File.delete(diskfile)
-    end
+    FileUtils.rm_f(diskfile) if disk_filename.present?
     Dir[thumbnail_path("*")].each do |thumb|
       File.delete(thumb)
     end

lib/redmine/thumbnail.rb

@@ -43,9 +43,7 @@ module Redmine
         return nil if is_pdf && mime_type != "application/pdf"
 
         directory = File.dirname(target)
-        unless File.exist?(directory)
-          FileUtils.mkdir_p directory
-        end
+        FileUtils.mkdir_p directory
         size_option = "#{size}x#{size}>"
 
         if is_pdf

lib/redmine/utils.rb

@@ -51,9 +51,7 @@ module Redmine
 
       def save_upload(upload, path)
         directory = File.dirname(path)
-        unless File.exist?(directory)
-          FileUtils.mkdir_p directory
-        end
+        FileUtils.mkdir_p directory
         File.open(path, "wb") do |f|
           if upload.respond_to?(:read)
             buffer = ""