Fix the error
```homestead-7: Creating and registering the VM...
An error occurred while executing a PowerShell script. This error
is shown below. Please read the error message and see if this is
a configuration error with your system. If it is not, then please
report a bug.
Script: import_vm_vmcx.ps1
Error:
At C:\Program Files
(x86)\HashiCorp\Vagrant\embedded\gems\gems\vagrant-1.9.4\plugins\providers\hyper v\scripts\import_vm_vmcx.ps1:18 char:37
+ [string]$differencing_disk=$null
+ ~
Missing ')' in function parameter list.
At C:\Program Files
(x86)\HashiCorp\Vagrant\embedded\gems\gems\vagrant-1.9.4\plugins\providers\hyper v\scripts\import_vm_vmcx.ps1:20 char:1
+ )
+ ~
Unexpected token ')' in expression or statement.
+ CategoryInfo : ParserError: (:) [], ParseException
+ FullyQualifiedErrorId : MissingEndParenthesisInFunctionParameterList
```
It was failing to create files below the machines\default\hyperv folder, rather it was creating folders named 'hypervSnapshots', 'hypervVirtual Hard Disks', and 'hypervVirtual Machines'. This was causing the files to not be removed when destroying the vm, and an error when subsequently bringing it up again.
Implemented the differencing disk for vmcx.
This means the disk is now copied by Hyper-V (Powershell) instead of Ruby for new machines.
This does mean EFI Firmware now does work for machines since it is quite a feep copy. Compare-VM will report incompatibilities should they be found.
Use the version of Hyper-V instead of Powershell to determine which
exception is thrown by Get-VM. Also fixing an invalid catch statement,
since Powershell can not use variables to match thrown exceptions in
catch.
Previously, there was no one gesture that would start a VM if it was not
running and run the appropriate provisioners regardless of its original
state. `vagrant up` did nothing if the VM was running, while
`vagrant provision` did nothing if the VM was not running.
Change the semantics of `vagrant up`, via the start actions of the providers,
to go through the provisioning logic even if the VM is already running.
The semantics of `run: "once"` vs `run: "always"` are respected.
Tested with the VirtualBox provider but not the others.
Resolves#4421
Arjan Weurding
Bjorn Brala
Patrick Lang
Chris Roberts
Brian Retford
Jake Ballard
tfanning
Rory Plaire
Ray Ruvinskiy
Seth Vargo
Jon Topper
Matt Wrock
Marchenko Alexandr
Kevin Blair
Luke Bakken
Mitchell Hashimoto
caleblloyd