[Hyper-V] Can no longer snapshot

[ricab]

Attempting to snapshot fails on Hyper-V:

PS C:\> multipass snapshot assisting-leafroller -n s1
snapshot failed: Failure while looking for snapshot name

Some verbosity helps uncover the problem:

PS C:\> multipass snapshot assisting-leafroller -n s1 -vvvv
[2024-10-18T20:24:58.172] [trace] [assisting-leafroller] [8892] Cmdlet: 'Get-VM -Name assisting-leafroller | Select-Object -ExpandProperty State'
[2024-10-18T20:24:59.218] [trace] [assisting-leafroller] Off
[2024-10-18T20:24:59.218] [trace] [assisting-leafroller] [8892] Output: Off
[2024-10-18T20:24:59.218] [trace] [assisting-leafroller] [8892] Cmdlet exit status is 'true'
[2024-10-18T20:24:59.218] [debug] [assisting-leafroller] [8892] Cmdlet: 'Get-VMCheckpoint -VMName assisting-leafroller -Name "@s1"'
[2024-10-18T20:25:00.280] [warning] [powershell.exe] Get-VMCheckpoint : Unable to find a snapshot matching the given criteria.

[2024-10-18T20:25:00.280] [warning] [powershell.exe] At line:1 char:1
+ Get-VMCheckpoint -VMName assisting-leafroller -Name "@s1"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (:) [Get-VMSnapshot], VirtualizationException


[2024-10-18T20:25:00.280] [trace] [assisting-leafroller]
[2024-10-18T20:25:00.296] [warning] [assisting-leafroller] [8892] stderr: Get-VMCheckpoint : Unable to find a snapshot matching the given criteria.
At line:1 char:1
+ Get-VMCheckpoint -VMName assisting-leafroller -Name "@s1"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (:) [Get-VMSnapshot], VirtualizationException
    + FullyQualifiedErrorId : ObjectNotFound,Microsoft.HyperV.PowerShell.Commands.GetVMSnapshot


[2024-10-18T20:25:00.296] [trace] [assisting-leafroller] [8892] Output:
[2024-10-18T20:25:00.296] [debug] [assisting-leafroller] [8892] Cmdlet exit status is 'false'
[2024-10-18T20:25:00.296] [warning] [assisting-leafroller] Get-VMCheckpoint failed with unexpected output:
snapshot failed: Failure while looking for snapshot name

Since the fix to #1632 was put in place with the stdout/stderr separation, the output of Get-VMSnapshot no longer matches expectations: Get-VMCheckpoint failed with unexpected output:. No output whatsoever, as stderr is now just logged and discarded.

Additional info

• multipass version 1.14.1