Catlet VMs are not exportable in Hyper-V

[ChristopherMann]

VMs which were created with eryph cannot be exported with Hyper-V tools.

Replication procedure:

1. Create a new catlet VM with New-Catlet -Parent ... -Name myvm
2. Export the created VM in Hyper-V with: Export-VM -Name myvm -Path ...

The export fails with an error message like this:

Export-VM: Failed to copy file during export.

Failed to copy file from '...' to '...': The file exists. (0x80070050).

AB#579

[fw2568]

Proposal: when genes are extracted the filename is replaced by the first 10 chars the gene hash (like in a git commit). During attach the name reference (sda, sdb) has to be replaced with the hash part by lookup of gene hash from metadata.