cleanup so gravatar download failures are consistent

previously we would ignore socket error, but this would mean that
there could be conditions where we would keep trying to download
gravatars forever (in an hourly job)

app/models/user_avatar.rb

@@ -13,7 +13,7 @@ class UserAvatar < ActiveRecord::Base
   def update_gravatar!
     DistributedMutex.synchronize("update_gravatar_#{user_id}") do
       begin
-        self.update_columns(last_gravatar_download_attempt: Time.now)
+        self.update!(last_gravatar_download_attempt: Time.now)
 
         max = Discourse.avatar_sizes.max
         email_hash = user_id == Discourse::SYSTEM_USER_ID ? User.email_hash("info@discourse.org") : user.email_hash
@@ -47,17 +47,12 @@ class UserAvatar < ActiveRecord::Base
               end
 
               gravatar_upload&.destroy!
-              self.gravatar_upload = upload
+              self.update!(gravatar_upload: upload)
-              save!
             end
           end
         end
-      rescue OpenURI::HTTPError
-        save!
-      rescue SocketError
-        # skip saving, we are not connected to the net
       ensure
-        tempfile.try(:close!)
+        tempfile&.close!
       end
     end
   end

spec/models/user_avatar_spec.rb

@@ -74,7 +74,9 @@ describe UserAvatar do
 
         FileHelper.expects(:download).raises(SocketError)
 
-        expect { avatar.update_gravatar! }.to_not change { Upload.count }
+        expect do
+          expect { avatar.update_gravatar! }.to raise_error(SocketError)
+        end.to_not change { Upload.count }
 
         expect(avatar.last_gravatar_download_attempt).to eq(Time.now)
       end