fix wait boot_command regex.

Resolves #4268

builder/qemu/step_type_boot_command.go

@@ -144,6 +144,7 @@ func vncSendString(c *vnc.ClientConn, original string) {
 	special["<rightShift>"] = 0xFFE2
 
 	shiftedChars := "~!@#$%^&*()_+{}|:\"<>?"
+	waitRe := regexp.MustCompile(`^<wait([0-9]+[hms])>`)
 
 	// TODO(mitchellh): Ripe for optimizations of some point, perhaps.
 	for len(original) > 0 {
@@ -339,16 +340,13 @@ func vncSendString(c *vnc.ClientConn, original string) {
 			continue
 		}
 
-		if strings.HasPrefix(original, "<wait") && strings.HasSuffix(original, ">") {
-			re := regexp.MustCompile(`<wait([0-9hms]+)>$`)
-			dstr := re.FindStringSubmatch(original)
-			if len(dstr) > 1 {
-				log.Printf("Special code %s found, sleeping", dstr[0])
-				if dt, err := time.ParseDuration(dstr[1]); err == nil {
-					time.Sleep(dt)
-					original = original[len(dstr[0]):]
-					continue
-				}
+		waitMatch := waitRe.FindStringSubmatch(original)
+		if len(waitMatch) > 1 {
+			log.Printf("Special code %s found, sleeping", waitMatch[0])
+			if dt, err := time.ParseDuration(waitMatch[1]); err == nil {
+				time.Sleep(dt)
+				original = original[len(waitMatch[0]):]
+				continue
 			}
 		}