Packer log: Error deleting VM

packer-config.json

{
	"variables"       : {
		"source_name"		    : "centos-7.3-x86_64-raw-r1",
		"headless"          : "false",
		"http_proxy"        : "{{env `http_proxy`}}",
		"https_proxy"       : "{{env `https_proxy`}}",
		"memory"            : "2048",
		"metadata"          : "packer/floppy/dummy_metadata.json",
		"name"              : "centos-7.3",
		"no_proxy"          : "{{env `no_proxy`}}",
		"template"          : "centos-7.3-x86_64-dev-r1",
		"scripts_root"		  : "packer/scripts/dev/centos",
		"version"           : "TIMESTAMP"
	},
	"builders"        : [
		{
			"type"                    : "virtualbox-ovf",
			"source_path"             : "output/virtualbox/{{user `source_name`}}/{{user `source_name`}}.ovf",
			"ssh_password"            : "vagrant",
			"ssh_port"                : 22,
			"ssh_username"            : "root",
			"ssh_wait_timeout"        : "45s",
			"guest_additions_path"    : "VBoxGuestAdditions.iso",
			"shutdown_command"        : "echo 'vagrant'|sudo -S /sbin/halt -h -p",
			"output_directory"        : "output/virtualbox/{{user `template`}}",
			"virtualbox_version_file" : ".vbox_version",
			"headless"                : "{{ user `headless` }}",
			"boot_wait"               : "30s",
			"vm_name"                 : "{{ user `template` }}"
		}
	],
	"post-processors" : [
		{
			"output"              : "output/vagrant/{{user `template`}}.{{.Provider}}.box",
			"type"                : "vagrant",
			"keep_input_artifact" : true
		}
	],
	"provisioners"    : [
		{
			"destination" : "/tmp/bento-metadata.json",
			"source"      : "{{user `metadata`}}",
			"type"        : "file"
		},
		{
			"environment_vars" : [
				"HOME_DIR=/home/vagrant",
				"http_proxy={{user `http_proxy`}}",
				"https_proxy={{user `https_proxy`}}",
				"no_proxy={{user `no_proxy`}}"
			],
			"execute_command"  : "echo 'vagrant' | {{.Vars}} sudo -S -E sh -eux '{{.Path}}'",
			"scripts"          : [
				"{{user `scripts_root`}}/common/install-common-libs.sh"
			],
			"type"             : "shell"
		}
	]
}

packer-log

$ packer build packer/templates/centos-7-dev.json
virtualbox-ovf output will be in this color.

==> virtualbox-ovf: Downloading or copying Guest additions
    virtualbox-ovf: Downloading or copying: file:///E:/Program%20Files/Oracle/VirtualBox/VBoxGuestAdditions.iso
==> virtualbox-ovf: Downloading or copying OVF/OVA
    virtualbox-ovf: Downloading or copying: file:///F:/Projects/Personal/sysops/sysops-packer/output/virtualbox/centos-7.3-x86_64-raw-r1/centos-7.3-x86_64-raw-r1.ovf
==> virtualbox-ovf: Importing VM: F:/Projects/Personal/sysops/sysops-packer/output/virtualbox/centos-7.3-x86_64-raw-r1/centos-7.3-x86_64-raw-r1.ovf
==> virtualbox-ovf: Creating forwarded port mapping for communicator (SSH, WinRM, etc) (host port 3383)
==> virtualbox-ovf: Starting the virtual machine...
==> virtualbox-ovf: Waiting 30s for boot...
==> virtualbox-ovf: Typing the boot command...
==> virtualbox-ovf: Waiting for SSH to become available...
==> virtualbox-ovf: Timeout waiting for SSH.
==> virtualbox-ovf: Unregistering and deleting imported VM...
==> virtualbox-ovf: Error deleting VM: VBoxManage error: VBoxManage.exe: error: Cannot unregister the machine 'centos-7.3-x86_64-dev-r1' while it is locked
==> virtualbox-ovf: VBoxManage.exe: error: Details: code VBOX_E_INVALID_OBJECT_STATE (0x80bb0007), component MachineWrap, interface IMachine, callee IUnknown
==> virtualbox-ovf: VBoxManage.exe: error: Context: "Unregister(CleanupMode_DetachAllReturnHardDisksOnly, ComSafeArrayAsOutParam(aMedia))" at line 155 of file VBoxManageMisc.cpp
==> virtualbox-ovf: Deleting output directory...
Build 'virtualbox-ovf' errored: Timeout waiting for SSH.

==> Some builds didn't complete successfully and had errors:
--> virtualbox-ovf: Timeout waiting for SSH.

==> Builds finished but no artifacts were created.