support/testing/infra/emulator.py: support init=/bin/sh

The TestInitSystemNone bypasses the normal init and instead launches
directly into a shell. So it needs to bypass the login code and go
directly to a shell.

Signed-off-by: Brandon Maier <brandon.maier@collins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

support/testing/infra/emulator.py

@@ -133,6 +133,9 @@ class Emulator(object):
             self.qemu.expect("Password:")
             self.qemu.sendline(password)
 
+        self.connect_shell()
+
+    def connect_shell(self):
         extra_init_cmd = " && ".join([
             'export PAGER=cat',
             'dmesg -n 1',