support/testing/tests/package/test_python_boto3: use ext2 instead of cpio

The CPIO filesystem generated by the test_python_boto3 test is too
large, and doesn't fit as an initramfs in the 256MB of RAM available
in the versatilepb machine. This causes a "Initramfs unpacking failed:
write error" when booting, and many files being missing from the root
filesystem, ultimately causing the test to fail.

It would make sense to switch all test cases to use ext2 + a
hard-drive, but for now, let's fix the few test cases that are causing
problems.

Fixes:

  https://gitlab.com/buildroot.org/buildroot/-/jobs/2884635041

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
[yann.morin.1998@free.fr:
  - drop superfluous# BR2_TARGET_ROOTFS_TAR is not set
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

support/testing/tests/package/test_python_boto3.py

@@ -1,4 +1,5 @@
 from tests.package.test_python import TestPythonPackageBase
+import os
 
 
 class TestPythonPy3Boto3(TestPythonPackageBase):
@@ -7,6 +8,16 @@ class TestPythonPy3Boto3(TestPythonPackageBase):
         """
         BR2_PACKAGE_PYTHON3=y
         BR2_PACKAGE_PYTHON_BOTO3=y
+        BR2_TARGET_ROOTFS_EXT2=y
+        BR2_TARGET_ROOTFS_EXT2_SIZE="120M"
         """
     sample_scripts = ["tests/package/sample_python_boto3.py"]
     timeout = 10
+
+    def login(self):
+        ext2_file = os.path.join(self.builddir, "images", "rootfs.ext2")
+        self.emulator.boot(arch="armv5",
+                           kernel="builtin",
+                           options=["-drive", "file=%s,if=scsi,format=raw" % ext2_file],
+                           kernel_cmdline=["rootwait", "root=/dev/sda"])
+        self.emulator.login()