do not use grep to test if sysroot is mounted

modules.d/99base/init

@@ -107,7 +107,7 @@ getarg 'break=mount' && emergency_shell
 # be sourced any number of times. As soon as one suceeds, no more are sourced.
 i=0
 while :; do
-    grep -q '/sysroot' /proc/mounts && break;
+    [ -d "$NEWROOT/proc" ] && break;
 
     for f in /mount/*.sh; do
        [ -x "$f" ] && . "$f";