[macOS] Multipass loses mounts on restart

**Edit**

- Look for the comments instead of this original Issue description.
- TL;DR `multipass restart` after `umount` of a classic mount causes instability in Multipass 1.14.0 (on macOS; at least Intel)
- Work-around: instead of `multipass restart`, use separate `multipass stop` and `multipass start` commands.

*Original problem description follows*
---

**Describe the bug**

I updated the Ubuntu stack today and immediately restarted the VM (because there was a new kernel the `apt` output suggests this). During the restart I get an error message.

This makes me think perhaps the kernel update and the losing of the mounts are related.

**To Reproduce**

1. It is a bit difficult to reproduce this, since one would need an upstream kernel update to be available. Once that is the case:

```
$ sudo apt update; sudo apt upgrade
[...]

Pending kernel upgrade!
Running kernel version:
6.8.0-40-generic
Diagnostics:
The currently running kernel version is not the expected kernel version 6.8.0-41-generic.

Restarting the system to load the new kernel will not be handled automatically, so you should consider rebooting.

No services need to be restarted.

No containers need to be restarted.

No user sessions are running outdated binaries.

No VM guests are running outdated hypervisor (qemu) binaries on this host.
```

2. Exit from VMs and:

```
$ mp restart rust-emb
Removing mount "/home/ubuntu/Rustyard" from 'rust-emb': [ssh proc] failed to open session channel: 'Socket error: Connection reset by peer'
Removing mount "/home/ubuntu/VL53L5CX_rs" from 'rust-emb': ssh connection failed: 'Socket error: Connection reset by peer'
```

**Expected behavior**

I would like the mounts to have remained.

**Logs**

>Please provide logs from the daemon, see [accessing logs](https://multipass.run/docs/accessing-logs) on where to find them on your platform.

Logs (no errors)

```
[2024-08-21T09:02:54.724] [debug] [async task] fetch manifest periodically
[2024-08-21T09:03:04.722] [warning] [url downloader] Error getting https://cloud-images.ubuntu.com/releases/streams/v1/index.json: Network timeout - trying cache.
[2024-08-21T09:03:04.722] [warning] [url downloader] Cannot retrieve headers for https://cdimage.ubuntu.com/ubuntu-core/18/stable/current/ubuntu-core-18-amd64.img.xz: Network timeout
[2024-08-21T09:03:04.722] [warning] [url downloader] Error getting https://cloud-images.ubuntu.com/buildd/daily/streams/v1/index.json: Network timeout - trying cache.
[2024-08-21T09:03:04.722] [warning] [url downloader] Cannot retrieve headers for https://cdimage.ubuntu.com/ubuntu-core/20/stable/current/ubuntu-core-20-amd64.img.xz: Network timeout
[2024-08-21T09:03:04.722] [warning] [url downloader] Cannot retrieve headers for https://cdimage.ubuntu.com/ubuntu-core/16/stable/current/ubuntu-core-16-amd64.img.xz: Network timeout
[2024-08-21T09:03:04.723] [warning] [url downloader] Cannot retrieve headers for https://cdimage.ubuntu.com/ubuntu-core/22/stable/current/ubuntu-core-22-amd64.img.xz: Network timeout
[2024-08-21T09:03:04.723] [warning] [VMImageHost] Could not update manifest: failed to download from 'https://cdimage.ubuntu.com/ubuntu-core/16/stable/current/ubuntu-core-16-amd64.img.xz': Operation canceled
[2024-08-21T09:03:14.723] [warning] [url downloader] Error getting https://cloud-images.ubuntu.com/buildd/daily/streams/v1/com.ubuntu.cloud:daily:download.json: Network timeout - trying cache.
[2024-08-21T09:08:43.412] [debug] [rust-emb] QMP: {"timestamp": {"seconds": 1724220523, "microseconds": 412178}, "event": "RTC_CHANGE", "data": {"offset": 0, "qom-path": "/machine/unattached/device[5]/rtc"}}

[2024-08-21T09:14:45.931] [debug] [ssh session] Executing 'findmnt --type 9p | grep '/home/ubuntu/Rustyard m9586b90902ea3195b09af3dd6e5645''
[2024-08-21T09:14:47.007] [debug] [ssh session] Executing 'findmnt --type 9p | grep '/home/ubuntu/Embassy-playground-2024 me67e8b88cd6831cd9f2edd9777d03d''
[2024-08-21T09:14:47.130] [info] [qemu-mount-handler] Stopping native mount "/home/ubuntu/Embassy-playground-2024" in instance 'rust-emb'
[2024-08-21T09:14:47.159] [debug] [ssh session] Executing 'if mountpoint -q /home/ubuntu/Embassy-playground-2024; then sudo umount /home/ubuntu/Embassy-playground-2024; else true; fi'
[2024-08-21T09:14:47.406] [debug] [ssh session] Executing 'findmnt --type 9p | grep '/home/ubuntu/VL53L5CX_rs m10ff1dc258763069a8c3c573cf2864''
[2024-08-21T09:14:47.528] [info] [qemu-mount-handler] Stopping native mount "/home/ubuntu/VL53L5CX_rs" in instance 'rust-emb'
[2024-08-21T09:14:47.554] [debug] [ssh session] Executing 'if mountpoint -q /home/ubuntu/VL53L5CX_rs; then sudo umount /home/ubuntu/VL53L5CX_rs; else true; fi'
[2024-08-21T09:14:47.681] [debug] [daemon] Rebooting rust-emb
[2024-08-21T09:14:47.681] [debug] [ssh session] Executing 'sudo systemctl stop ssh'
[2024-08-21T09:14:47.718] [debug] [ssh session] Executing 'sudo reboot'
[2024-08-21T09:14:47.773] [debug] [rust-emb] Dropping cached SSH session
[2024-08-21T09:14:47.773] [debug] [rust-emb] Waiting for SSH to be up
[2024-08-21T09:14:47.876] [debug] [rust-emb] Caching initial SSH session
[2024-08-21T09:14:47.927] [debug] [ssh session] Executing 'sudo /bin/bash -c 'P="/home/ubuntu/Rustyard"; while [ ! -d "$P/" ]; do P="${P%/*}"; done; echo $P/''
[2024-08-21T09:14:48.032] [warning] [daemon] Removing mount "/home/ubuntu/Rustyard" from 'rust-emb': [ssh proc] failed to open session channel: 'Socket error: Connection reset by peer'

[2024-08-21T09:14:48.527] [debug] [ssh session] Executing 'sudo /bin/bash -c 'P="/home/ubuntu/Embassy-playground-2024"; while [ ! -d "$P/" ]; do P="${P%/*}"; done; echo $P/''
[2024-08-21T09:14:48.759] [debug] [ssh session] Executing 'sudo mount -t 9p me67e8b88cd6831cd9f2edd9777d03d /home/ubuntu/Embassy-playground-2024 -o trans=virtio,version=9p2000.L,msize=536870912'
[2024-08-21T09:14:48.784] [warning] [daemon] Removing mount "/home/ubuntu/VL53L5CX_rs" from 'rust-emb': ssh connection failed: 'Socket error: Connection reset by peer'

[2024-08-21T09:14:52.702] [debug] [rust-emb] QMP: {"timestamp": {"seconds": 1724220892, "microseconds": 701567}, "event": "RESET", "data": {"guest": true, "reason": "guest-reset"}}

[2024-08-21T09:14:52.702] [info] [rust-emb] VM restarting
[2024-08-21T09:14:52.703] [debug] [rust-emb] Dropping cached SSH session
[2024-08-21T09:15:11.737] [debug] [ssh session] Executing 'findmnt --type 9p | grep '/home/ubuntu/Embassy-playground-2024 me67e8b88cd6831cd9f2edd9777d03d''
[2024-08-21T09:15:12.133] [debug] [rust-emb] Waiting for SSH to be up
[2024-08-21T09:15:12.133] [debug] [rust-emb] QMP: {"timestamp": {"seconds": 1724220893, "microseconds": 219597}, "event": "RTC_CHANGE", "data": {"offset": 0, "qom-path": "/machine/unattached/device[5]/rtc"}}
{"timestamp": {"seconds": 1724220893, "microseconds": 402854}, "event": "RTC_CHANGE", "data": {"offset": 0, "qom-path": "/machine/unattached/device[5]/rtc"}}

[2024-08-21T09:15:12.161] [debug] [rust-emb] Caching initial SSH session
[2024-08-21T09:15:12.193] [debug] [ssh session] Executing 'sudo /bin/bash -c 'P="/home/ubuntu/Embassy-playground-2024"; while [ ! -d "$P/" ]; do P="${P%/*}"; done; echo $P/''
[2024-08-21T09:15:12.393] [debug] [ssh session] Executing 'sudo mount -t 9p me67e8b88cd6831cd9f2edd9777d03d /home/ubuntu/Embassy-playground-2024 -o trans=virtio,version=9p2000.L,msize=536870912'
[2024-08-21T09:15:59.433] [debug] [rust-emb] QMP: {"timestamp": {"seconds": 1724220959, "microseconds": 433605}, "event": "RTC_CHANGE", "data": {"offset": 0, "qom-path": "/machine/unattached/device[5]/rtc"}}

[2024-08-21T09:17:54.749] [debug] [async task] fetch manifest periodically
[2024-08-21T09:18:04.748] [warning] [url downloader] Cannot retrieve headers for https://cdimage.ubuntu.com/ubuntu-core/20/stable/current/ubuntu-core-20-amd64.img.xz: Network timeout
[2024-08-21T09:18:04.748] [warning] [url downloader] Error getting https://cloud-images.ubuntu.com/buildd/daily/streams/v1/index.json: Network timeout - trying cache.
[2024-08-21T09:18:04.748] [warning] [url downloader] Cannot retrieve headers for https://cdimage.ubuntu.com/ubuntu-core/22/stable/current/ubuntu-core-22-amd64.img.xz: Network timeout
[2024-08-21T09:18:04.748] [warning] [url downloader] Cannot retrieve headers for https://cdimage.ubuntu.com/ubuntu-core/18/stable/current/ubuntu-core-18-amd64.img.xz: Network timeout
[2024-08-21T09:18:04.749] [warning] [url downloader] Error getting https://cloud-images.ubuntu.com/releases/streams/v1/index.json: Network timeout - trying cache.
[2024-08-21T09:18:04.749] [warning] [url downloader] Cannot retrieve headers for https://cdimage.ubuntu.com/ubuntu-core/16/stable/current/ubuntu-core-16-amd64.img.xz: Network timeout
[2024-08-21T09:18:04.750] [warning] [VMImageHost] Could not update manifest: failed to download from 'https://cdimage.ubuntu.com/ubuntu-core/16/stable/current/ubuntu-core-16-amd64.img.xz': Operation canceled
[2024-08-21T09:18:14.749] [warning] [url downloader] Error getting https://cloud-images.ubuntu.com/buildd/daily/streams/v1/com.ubuntu.cloud:daily:download.json: Network timeout - trying cache.
[2024-08-21T09:27:01.442] [debug] [rust-emb] QMP: {"timestamp": {"seconds": 1724221621, "microseconds": 442521}, "event": "RTC_CHANGE", "data": {"offset": 0, "qom-path": "/machine/unattached/device[5]/rtc"}}
```

- OS: macOS 14.6.1 (Intel)
- `multipass version`

```
multipass 1.14.0-rc1.2439+g95e4d16a3.mac
multipassd 1.14.0-rc1.2439+g95e4d16a3.mac
```

- `multipass info`

```
Name: rust-emb
State: Running
Snapshots: 0
IPv4: 192.168.64.120
Release: Ubuntu 24.04 LTS
Image hash: d2377667ea95 (Ubuntu 24.04 LTS)
CPU(s): 3
Load: 0.00 0.00 0.00
Disk usage: 5.2GiB out of 17.4GiB
Memory usage: 402.2MiB out of 5.8GiB
Mounts: /Users/asko/Git/Embassy-playground-2024 => /home/ubuntu/Embassy-playground-2024
UID map: 501:default
GID map: 20:default
```

One mount (out of three) seems to have survived. Don't know why.

- `multipass get local.driver`

```
qemu
```

**Additional context**

Using a RC-1 because of issues with 1.14.0 proper.

The mounts were made using `--type=native` (I always do that), e.g.

```
$ mp mount --type=native Rustyard rust-emb:/home/ubuntu/Rustyard
```

Work-around:

- recreate the mounts manually

Start by reproducing the issue on macOS with the QEMU driver: create a native mount, unmount it, and run `multipass restart`; compare the result with separate `multipass stop` and `multipass start` commands. Done means native mounts remain available after the restart without instability or manual recreation.

Written by the indexing model from the issue text.