[horizon] Falvor list in Horizon does not match console output

[Sergii Turivnyi]

Description of the environment:
  MOS 9.2
  1 controller
  1 compute
default configuration

Detailed bug description:
 Flavor list in Horizon does not match console output

Steps to reproduce:
 Navigate to console as admin
 Create new flavor
    # nova flavor-create bm_flavor auto 3072 150 1
 Check flavor was created successfully (see attachment)
 Boot instance
 Navigate to Horizon as admin
 Resize instance in Horizon
 Navigate to the "Flavor Choice" menu
 Select created flavor "bm_flavor"

Expected result:
 Flavor in the drop-down list
 Admin can select flavor from the list

Actual result:
 Flavor is not exists in the drop-down list (see attachment)

        <select class="form-control" id="id_flavor" name="flavor">
<option value="" selected="selected">Select a New Flavor</option>
<option value="993c4c1b-4790-42a5-b336-e76a05dce0d4">m1.micro</option>
<option value="1">m1.tiny</option>
<option value="2">m1.small</option>
<option value="3">m1.medium</option>
<option value="4">m1.large</option>
<option value="5">m1.xlarge</option>

Workaround:
 Working in command line

[Sergii Turivnyi (sturivnyi)]

Root cause:
Instance can't be updated to new flavor because this instance already uses flavor