Invalid condition "<%boot%>" raised when parse 'repeat' args

[huangtianhua]

Create a stack with following template:

  parameters:
    boot_flag:
      type: comma_delimited_list
      default: [true, false]
  resources:
    my_ser:
    type: OS::Nova::Server
    properties:
      name: my_server
      flavor: 1
      block_device_mapping:
        repeat:
          template:
            device_name: {if: [<%boot%>, 'vda', 'vdb']}
            volume_id: {if: [<%boot%>, {get_resource: boot_vol}, {get_resource: data_vol}]}
          for_each:
            <%boot%>: {get_param: boot_flag}

expected: stack create success
actually: an error raised: resources.my_ser.properties.block_device_mapping.repeat.template.device_name.if: : Invalid condition "<%boot%>"

The reason is that 'repeat' function can not be parsed, because the we parse its args first, when we parse 'if', <%boot%> has not been replaced.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/449098

[OpenStack Infra (hudson-openstack)]

Change abandoned by Zane Bitter (<email address hidden>) on branch: master
Review: https://review.opendev.org/449098