don't update customer.email with shipping

Stripe/PublicHeaders/STPPaymentContext.h

@@ -153,7 +153,10 @@ NS_ASSUME_NONNULL_BEGIN
  *  When your user enters a new shipping address, PaymentContext will save it to 
  *  the current customer object. When PaymentContext loads, if you haven't
  *  manually set a prefilled value, any shipping information saved on the customer 
- *  will be used to prefill the shipping address form.
+ *  will be used to prefill the shipping address form. Note that because your
+ *  customer's email may not be the same as the email provided with their shipping
+ *  info, PaymentContext will not prefill the shipping form's email using your 
+ *  customer's email.
  *
  *  You should not rely on the shipping information stored on the Stripe customer 
  *  for order fulfillment, as your user may change this information if they make 

Stripe/STPCustomer.m

@@ -83,9 +83,6 @@
         shipping.state = shippingDict[@"address"][@"state"];
         shipping.postalCode = shippingDict[@"address"][@"postal_code"];
         shipping.country = shippingDict[@"address"][@"country"];
-        // Note: email is currently one level above in the customer API,
-        // but the SDK stores it in customer.shippingAddress
-        shipping.email = dict[@"email"];
         customer.shippingAddress = shipping;
     }
     NSMutableArray *sources = [NSMutableArray array];

Stripe/STPCustomerContext.m

@@ -149,7 +149,6 @@ static NSTimeInterval const DefaultCachedCustomerMaxAge = 60;
         NSMutableDictionary *params = [NSMutableDictionary new];
         params[@"shipping"] = [STPAddress shippingInfoForChargeWithAddress:shipping
                                                             shippingMethod:nil];
-        params[@"email"] = shipping.email;
         [STPAPIClient updateCustomerWithParameters:[params copy]
                                           usingKey:ephemeralKey
                                         completion:^(STPCustomer *customer, NSError *error) {