[Rails5] Fix `storage_counter` helper

Since rails 5 beta 2 support of petabytes and exabytes were added to the
`number_to_human*` methods.
See https://github.com/rails/rails/pull/22759

So for rails5 the comma separator gets shown for big numbers (EBs).

spec/helpers/storage_helper_spec.rb

-require 'spec_helper'
+require "spec_helper"
 
 describe StorageHelper do
-  describe '#storage_counter' do
-    it 'formats bytes to one decimal place' do
-      expect(helper.storage_counter(1.23.megabytes)).to eq '1.2 MB'
+  describe "#storage_counter" do
+    it "formats bytes to one decimal place" do
+      expect(helper.storage_counter(1.23.megabytes)).to eq("1.2 MB")
     end
 
-    it 'does not add decimals for sizes < 1 MB' do
-      expect(helper.storage_counter(23.5.kilobytes)).to eq '24 KB'
+    it "does not add decimals for sizes < 1 MB" do
+      expect(helper.storage_counter(23.5.kilobytes)).to eq("24 KB")
     end
 
-    it 'does not add decimals for zeroes' do
-      expect(helper.storage_counter(2.megabytes)).to eq '2 MB'
+    it "does not add decimals for zeroes" do
+      expect(helper.storage_counter(2.megabytes)).to eq("2 MB")
     end
 
-    it 'uses commas as thousands separator' do
-      expect(helper.storage_counter(100_000_000_000_000_000)).to eq '90,949.5 TB'
+    it "uses commas as thousands separator" do
+      if Gitlab.rails5?
+        expect(helper.storage_counter(100_000_000_000_000_000_000_000)).to eq("86,736.2 EB")
+      else
+        expect(helper.storage_counter(100_000_000_000_000_000)).to eq("90,949.5 TB")
+      end
     end
   end
 end