Fix parsing for NetBSD sleep error message

testsuite/expect/globals

@@ -210,7 +210,7 @@ cset max_stress_tasks 4
 #
 # The error message that the "sleep" command prints when we run "sleep aaa".
 #
-cset sleep_error_message "(invalid time interval)|(bad character in argument)"
+cset sleep_error_message "(invalid time interval)|(bad character in argument)|(usage: sleep seconds)"
 
 # Other common variables
 set alpha                "\[a-zA-Z\]+"

testsuite/expect/test28.2

@@ -181,7 +181,7 @@ for {set index 0} {$index < $array_end} {incr index} {
 	set err_match 0
 	spawn $bin_cat test$test_id-$job_id\_$index\.error
 	expect {
-		-re "invalid time" {
+		-re "$sleep_error_message" {
 			send_user "\nDo not worry this error is expected\n"
 			incr err_match
 		}