imgs/boot: fix failure in bootup

imgs/boot/bin/prepare_turris_image

@@ -15,6 +15,7 @@ wget "https://repo.turris.cz/hbk/medkit/omnia-medkit-latest.tar.gz" -O medkit.ta
 # Repack as CPIO
 mkdir root
 tar -xzf medkit.tar.gz -C root
+ln -sf /sbin/init root/init
 ( cd root && find . | cpio -H newc -o > ../root.cpio )
 mkimage -A arm -O linux -T ramdisk -C none -d root.cpio root.uimage
 

nsfarm/board.py

@@ -76,7 +76,8 @@ class Board():
         # Wait for bootup
         self.pexpect.expect_exact(["Router Turris successfully started.", ])
         # Note Shell sends new line which opens terminal for it
-        return cli.Shell(self.pexpect)
+        # TODO why this flush timeouts?
+        return cli.Shell(self._pexpect, flush=False)
 
     def serial_pexpect(self):
         """Returns pexpect handle to serial TTY interface.