Script wasn't able to handle path that Packer used to create VM in the first place:
"==> hyperv-iso: Copying to output dir...
==> hyperv-iso: Error exporting vm: PowerShell error: Move-Item : An object at the specified path C:\Users\HANNU~1.PIK does not exist.
==> hyperv-iso: At C:\Users\hannu.piki\AppData\Local\Temp\ps520830935.ps1:13 char:1
==> hyperv-iso: + Move-Item -Path "$srcPath/$vhdDirName" -Destination $dstPath -Verbose
==> hyperv-iso: + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
==> hyperv-iso: + CategoryInfo : InvalidArgument: (:) [Move-Item], PSArgumentException
==> hyperv-iso: + FullyQualifiedErrorId : Argument,Microsoft.PowerShell.Commands.MoveItemCommand"
Used path was: C:\Users\HANNU~1.PIK\AppData\Local\Temp\packerhv616791918\export253729206\2016min
Real path was: C:\Users\hannu.piki\AppData\Local\Temp\packerhv616791918\export253729206\2016min