[VMSnapshotLinux] Install fails on RHEL 8.0 / Backups fails

**VMSnapshotLinux** extension fails on **RHEL 8.0** *(RedHat:RHEL:8:latest)*

## Error

```
[ExtensionOperationError] Non-zero exit code: 3, /var/lib/waagent/Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0/main/handle.sh install
[stdout]
2019/11/17 00:03:18.094280 INFO ExtHandler Added PID 53989 to cgroup /sys/fs/cgroup/cpu/walinuxagent.extensions/Microsoft.Azure.RecoveryServices.VMSnapshotLinux_1.0.9156.0
2019/11/17 00:03:18.103767 INFO ExtHandler Added PID 53989 to cgroup /sys/fs/cgroup/memory/walinuxagent.extensions/Microsoft.Azure.RecoveryServices.VMSnapshotLinux_1.0.9156.0

[stderr]
```

## shell.log
```
Mon Nov 18 00:05:10 UTC 2019- python version unknown
Mon Nov 18 00:05:10 UTC 2019- 3 returned from handle.py
Mon Nov 18 22:50:18 UTC 2019- python version unknown
Mon Nov 18 22:50:18 UTC 2019- 3 returned from handle.py
Tue Nov 19 00:09:59 UTC 2019- python version unknown
Tue Nov 19 00:09:59 UTC 2019- 3 returned from handle.py
Wed Nov 20 00:08:03 UTC 2019- python version unknown
Wed Nov 20 00:08:03 UTC 2019- 3 returned from handle.py
Thu Nov 21 00:07:52 UTC 2019- python version unknown
Thu Nov 21 00:07:52 UTC 2019- 3 returned from handle.py
Fri Nov 22 00:12:01 UTC 2019- python version unknown
Fri Nov 22 00:12:01 UTC 2019- 3 returned from handle.py
```

## CommandExecution.log
```
2019/11/18 00:05:11.980213 INFO [Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0] Remove extension handler directory: /var/lib/waagent/Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0
2019/11/18 22:50:20.136935 INFO [Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0] Remove extension handler directory: /var/lib/waagent/Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0
2019/11/19 00:10:01.120451 INFO [Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0] Remove extension handler directory: /var/lib/waagent/Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0
2019/11/20 00:08:05.108843 INFO [Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0] Remove extension handler directory: /var/lib/waagent/Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0
2019/11/21 00:07:55.553155 INFO [Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0] Remove extension handler directory: /var/lib/waagent/Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0
2019/11/22 00:12:04.025365 INFO [Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0] Remove extension handler directory: /var/lib/waagent/Microsoft.Azure.RecoveryServices.VMSnapshotLinux-1.0.9156.0
```