Fix transitions for image_download and activation

Change-Id: I713ada52eef9d275c7d7596026e178c7382e8335
diff --git a/vendor/golang.org/x/sys/windows/env_windows.go b/vendor/golang.org/x/sys/windows/env_windows.go
index f482a9f..92ac05f 100644
--- a/vendor/golang.org/x/sys/windows/env_windows.go
+++ b/vendor/golang.org/x/sys/windows/env_windows.go
@@ -8,7 +8,6 @@
 
 import (
 	"syscall"
-	"unicode/utf16"
 	"unsafe"
 )
 
@@ -40,17 +39,11 @@
 	defer DestroyEnvironmentBlock(block)
 	blockp := uintptr(unsafe.Pointer(block))
 	for {
-		entry := (*[(1 << 30) - 1]uint16)(unsafe.Pointer(blockp))[:]
-		for i, v := range entry {
-			if v == 0 {
-				entry = entry[:i]
-				break
-			}
-		}
+		entry := UTF16PtrToString((*uint16)(unsafe.Pointer(blockp)))
 		if len(entry) == 0 {
 			break
 		}
-		env = append(env, string(utf16.Decode(entry)))
+		env = append(env, entry)
 		blockp += 2 * (uintptr(len(entry)) + 1)
 	}
 	return env, nil