nixpart0: Fix race condition in formatting devices

This adds a backport of rhinstaller/blivet#39 to the pinned blivet
version 0.17, it's addressing the following upstream bug:

https://bugzilla.redhat.com/show_bug.cgi?id=1196397

It has been reported at aszlig/nixpart#7 and tested by @manveru (the
issue reporter), thanks a lot.

Thanks also to @domenkozar for finding the upstream issue.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Reported-by: Michael Fellinger <m.fellinger@gmail.com>
Fixes: aszlig/nixpart#7

pkgs/tools/filesystems/nixpart/0.4/blivet.patch

@@ -37,3 +37,15 @@ index 705b93d..7268d71 100644
  
  # load the udev library
  libudev = CDLL(libudev)
+diff --git a/blivet/deviceaction.py b/blivet/deviceaction.py
+index 705b93d..60f8f32 100644
+--- a/blivet/deviceaction.py
++++ b/blivet/deviceaction.py
+@@ -467,6 +467,7 @@ def execute(self):
+ 
+                 self.device.disk.format.commitToDisk()
+ 
++            self.device.setup()
+             self.device.format.create(device=self.device.path,
+                                       options=self.device.formatArgs)
+