theres no good unbuffered linux utils...

scripts/ci/test-setup.sh

@@ -108,7 +108,7 @@ function wait_tty {
 		exit 1
 	fi
 
-	configure_tty "$1" "$2" ; cat "$1" | grep --line-buffered -m1 "$3"
+	configure_tty "$1" "$2" ; cat "$1" | ./scripts/ci/utils/wait_for.py "$3"
 }
 
 function start_record_tty {

scripts/ci/utils/wait_for.py

@@ -0,0 +1,21 @@
+#!/usr/bin/python3
+
+import sys
+import os
+
+if len(sys.argv) != 2:
+	print('usage: wait_for.py [pattern]')
+	exit(1)
+
+pattern = sys.argv[1].encode('utf-8')
+
+index = 0
+while True:
+	if index == len(pattern):
+		exit(0)
+
+	n = os.read(sys.stdin.fileno(), 1)
+	if n[0] == pattern[index]:
+		index += 1
+	else:
+		index = 0