Remove duplicate code in Redmine::Thumbnail.generate (#34969).

Patch by Go MAEDA.


git-svn-id: http://svn.redmine.org/redmine/trunk@20861 e93f8b46-1217-0410-a6f0-8f06a7374b81

lib/redmine/thumbnail.rb

@@ -34,16 +34,12 @@ module Redmine
       return nil if is_pdf && !gs_available?
 
       unless File.exists?(target)
+        # Make sure we only invoke Imagemagick if the file type is allowed
         mime_type = File.open(source) {|f| MimeMagic.by_magic(f).try(:type)}
         return nil if mime_type.nil?
         return nil if !ALLOWED_TYPES.include? mime_type
         return nil if is_pdf && mime_type != "application/pdf"
 
-        # Make sure we only invoke Imagemagick if the file type is allowed
-        unless File.open(source) {|f| ALLOWED_TYPES.include? MimeMagic.by_magic(f).try(:type)}
-          return nil
-        end
-
         directory = File.dirname(target)
         unless File.exists?(directory)
           FileUtils.mkdir_p directory