pmbootstrap chroot --install-blockdev: new option (MR 1946)

Create /dev/install inside the chroot from a block device, just like
done during the installation. This is useful for testing the Calamares
installer.

pmb/helpers/frontend.py

@@ -25,6 +25,7 @@ import pmb.helpers.run
 import pmb.helpers.aportupgrade
 import pmb.helpers.status
 import pmb.install
+import pmb.install.blockdevice
 import pmb.parse
 import pmb.qemu
 
@@ -132,6 +133,13 @@ def chroot(args):
         env["DISPLAY"] = os.environ.get("DISPLAY")
         env["XAUTHORITY"] = "/home/pmos/.Xauthority"
 
+    # Install blockdevice
+    if args.install_blockdev:
+        size_boot = 128 * 1024 * 1024  # 128 MiB
+        size_root = 4096 * 1024 * 1024  # 4 GiB
+        pmb.install.blockdevice.create_and_mount_image(args, size_boot,
+                                                       size_root)
+
     # Run the command as user/root
     if args.user:
         logging.info("(" + suffix + ") % su pmos -c '" +