Merge pull request stripe-ruby-mock#573 from MaicolBen/bug/token-replace-source

Fix replacing customer source when generates a new token

Author: alexmamonchik

lib/stripe_mock/request_handlers/tokens.rb

@@ -46,12 +46,12 @@ def create_token(route, method_url, params, headers)
         end
 
         if bank_account
-          token_id = generate_bank_token(bank_account)
+          token_id = generate_bank_token(bank_account.dup)
           bank_account = @bank_tokens[token_id]
 
           Data.mock_bank_account_token(params.merge :id => token_id, :bank_account => bank_account)
         else
-          token_id = generate_card_token(customer_card)
+          token_id = generate_card_token(customer_card.dup)
           card = @card_tokens[token_id]
 
           Data.mock_card_token(params.merge :id => token_id, :card => card)