Broken firmware image is not verified before upgrading

[ash111111-blip]

Issue:
Partially downloaded BMC image through TFTP is not verified before applying it on next reset.

Steps:
1.Check "ApplyTime" is "OnReset":
HTTP Get from https://<bmc_ip>/redfish/v1/UpdateService

Response:

"FirmwareInventory": {
    "@odata.id": "/redfish/v1/UpdateService/FirmwareInventory"
},
"HttpPushUri": "/redfish/v1/UpdateService",
"HttpPushUriOptions": {
    "HttpPushUriApplyTime": {
        "ApplyTime": "OnReset"
    }
},

2. Download Image
   curl -k -H "X-Auth-Token: $token" -X POST https://${bmc}/redfish/v1/UpdateService/Actions/UpdateService.SimpleUpdate -d '{"ImageURI":"tftp://<tftp_ip>/obmc-phosphor-image-transformers-20210330173445.static.mtd.all.tar"}'

3. When first time download tar image from tftp server completes around 85%, then submit Redfish POST command to download same image again. Redfish POST shows "Base.1.8.1.ServiceTemporarilyUnavailable" error but it still downloads after this error message show up.
   I used windows tftp server, so I can check download progress bar on window; There are "2" download progress bars popping up.

4. Do "ipmitool mc reset cold" when the second time download progress gets to 25% to 35%.

5. The bmc reboot (mc reset cold) crashes.

Please see the video for steps followed :
https://www.youtube.com/watch?v=0UfPNmw0X70&list=PLjZxgm7U9UoxGIMPnH_-FOHxDjtWDTyzM&index=9