Can't change quantity of line item with rules
I played around with the rules actions and got it to work with these settings &amp; the function I created to manually update the table:

    { "rules_1_gift_card_per_cart" : {
    "LABEL" : "1 Gift Card per cart",
    "PLUGIN" : "reaction rule",
    "REQUIRES" : [
      "rules",
      "rules_conditional",
      "commerce_giftcards",
      "commerce_cart",
      "commerce_rules_extra",
      "entity"
    ],
    "ON" : [
      "commerce_cart_product_add",
      "line_item_quantity_changed",
      "commerce_line_item_update"
    ],
    "IF" : [
      { "data_is" : { "data" : [ "commerce-line-item:type" ], "value" : "gift_certificate" } },
      { "AND" : [] },
      { "data_is" : {
          "data" : [ "commerce-line-item:quantity" ],
          "op" : "\u003E",
          "value" : "1"
        }
      }
    ],
    "DO" : [
      { "CONDITIONAL" : [
          {
            "IF" : { "data_is" : {
                "data" : [ "commerce-line-item:quantity" ],
                "op" : "\u003E",
                "value" : "1"
              }
            },
            "DO" : [
              { "data_set" : { "data" : [ "commerce-line-item:quantity" ], "value" : "1" } },
              { "drupal_message" : {
                  "message" : "Only one gift card per order.",
                  "type" : "warning",
                  "repeat" : 0
                }
              },
              { "commerce_giftcards_action_change_qty_one" : {
                  "order" : [ "commerce-line-item:order" ],
                  "line_item" : [ "commerce-line-item" ]
                }
              }
            ]
          }
        ]
      }
    ]
  }
}