allow to set ExecutionPolicy to none for powershell provisioner

this has the effect to not wrap the command, which will allow to know the exit status of a command in docker

provisioner/powershell/execution_policy.go

@@ -10,13 +10,14 @@ import (
 type ExecutionPolicy int
 
 const (
-	Bypass       ExecutionPolicy = 0
-	AllSigned    ExecutionPolicy = 1
-	Default      ExecutionPolicy = 2
-	RemoteSigned ExecutionPolicy = 3
-	Restricted   ExecutionPolicy = 4
-	Undefined    ExecutionPolicy = 5
-	Unrestricted ExecutionPolicy = 6
+	Bypass ExecutionPolicy = iota
+	AllSigned
+	Default
+	RemoteSigned
+	Restricted
+	Undefined
+	Unrestricted
+	None // not set
 )
 
 func (ep *ExecutionPolicy) Decode(v interface{}) (err error) {

provisioner/powershell/executionpolicy_enumer.go

@@ -7,9 +7,9 @@ import (
 	"fmt"
 )
 
-const _ExecutionPolicyName = "BypassAllSignedDefaultRemoteSignedRestrictedUndefinedUnrestricted"
+const _ExecutionPolicyName = "BypassAllSignedDefaultRemoteSignedRestrictedUndefinedUnrestrictedNone"
 
-var _ExecutionPolicyIndex = [...]uint8{0, 6, 15, 22, 34, 44, 53, 65}
+var _ExecutionPolicyIndex = [...]uint8{0, 6, 15, 22, 34, 44, 53, 65, 69}
 
 func (i ExecutionPolicy) String() string {
 	if i < 0 || i >= ExecutionPolicy(len(_ExecutionPolicyIndex)-1) {
@@ -18,7 +18,7 @@ func (i ExecutionPolicy) String() string {
 	return _ExecutionPolicyName[_ExecutionPolicyIndex[i]:_ExecutionPolicyIndex[i+1]]
 }
 
-var _ExecutionPolicyValues = []ExecutionPolicy{0, 1, 2, 3, 4, 5, 6}
+var _ExecutionPolicyValues = []ExecutionPolicy{0, 1, 2, 3, 4, 5, 6, 7}
 
 var _ExecutionPolicyNameToValueMap = map[string]ExecutionPolicy{
 	_ExecutionPolicyName[0:6]:   0,
@@ -28,6 +28,7 @@ var _ExecutionPolicyNameToValueMap = map[string]ExecutionPolicy{
 	_ExecutionPolicyName[34:44]: 4,
 	_ExecutionPolicyName[44:53]: 5,
 	_ExecutionPolicyName[53:65]: 6,
+	_ExecutionPolicyName[65:69]: 7,
 }
 
 // ExecutionPolicyString retrieves an enum value from the enum constants string name.

provisioner/powershell/provisioner.go

@@ -87,10 +87,14 @@ type EnvVarsTemplate struct {
 }
 
 func (p *Provisioner) defaultExecuteCommand() string {
-	return `powershell -executionpolicy ` + p.config.ExecutionPolicy.String() +
-		` "& { if (Test-Path variable:global:ProgressPreference)` +
+	baseCmd := `& { if (Test-Path variable:global:ProgressPreference)` +
 		`{set-variable -name variable:global:ProgressPreference -value 'SilentlyContinue'};` +
-		`. {{.Vars}}; &'{{.Path}}'; exit $LastExitCode }"`
+		`. {{.Vars}}; &'{{.Path}}'; exit $LastExitCode }`
+	if p.config.ExecutionPolicy == None {
+		return baseCmd
+	} else {
+		return fmt.Sprintf(`powershell -executionpolicy %s "%s"`, p.config.ExecutionPolicy, baseCmd)
+	}
 }
 
 func (p *Provisioner) Prepare(raws ...interface{}) error {