FIX: Regularly reset unknown extension of uploads

Discourse will try to detect the extension the next time the upload is needed. Maybe there was just a transient error the last time.

app/jobs/scheduled/weekly.rb

@@ -14,6 +14,7 @@ module Jobs
       MiniScheduler::Stat.purge_old
       Draft.cleanup!
       UserAuthToken.cleanup!
+      Upload.reset_unknown_extensions!
     end
   end
 end

app/models/upload.rb

@@ -359,6 +359,10 @@ class Upload < ActiveRecord::Base
     problems
   end
 
+  def self.reset_unknown_extensions!
+    Upload.where(extension: "unknown").update_all(extension: nil)
+  end
+
   private
 
   def short_url_basename

spec/models/upload_spec.rb

@@ -288,4 +288,15 @@ describe Upload do
     end
   end
 
+  describe '.reset_unknown_extensions!' do
+    it 'should reset the extension of uploads when it is "unknown"' do
+      upload1 = Fabricate(:upload, extension: "unknown")
+      upload2 = Fabricate(:upload, extension: "png")
+
+      Upload.reset_unknown_extensions!
+
+      expect(upload1.reload.extension).to eq(nil)
+      expect(upload2.reload.extension).to eq("png")
+    end
+  end
 end