Fix #463: Ignore exit code from parted (#465)

Parted often succeeds, but then returns a non-zero exit code, because
it can not inform the kernel of the changes.
In most cases this is not even necessary, so it really should not
fail there.
When the error was fatal, pmbootstrap will crash shortly afterwards
when it tried to mount or run mkfs on the partition anyway.

pmb/install/partition.py

@@ -59,7 +59,10 @@ def partition(args, size_boot):
     logging.info("(native) partition /dev/install (boot: " + mb_boot +
                  ", root: the rest)")
 
-    # Actual partitioning with 'parted'
+    # Actual partitioning with 'parted'. Using check=False, because parted
+    # sometimes "fails to inform the kernel". In case it really failed with
+    # partitioning, the follow-up mounting/formatting will not work, so it
+    # will stop there (see #463).
     commands = [
         ["mktable", "msdos"],
         ["mkpart", "primary", "ext2", "2048s", mb_boot],
@@ -68,7 +71,7 @@ def partition(args, size_boot):
     ]
     for command in commands:
         pmb.chroot.root(args, ["parted", "-s", "/dev/install"] +
-                        command)
+                        command, check=False)
 
     # Mount new partitions
     partitions_mount(args)