Fix test for failure to find space for device.

If the device ends up smaller than the format's min size we must have
run out of space. It's only okay for the device size to end up the
format's min size if that's what was asked for, whether explicitly or
by normalizing the specified target size.

blivet/devicefactory.py

@@ -706,7 +706,9 @@ def _set_size(self):
             log.error("device post-create method failed: %s", e)
             raise
         else:
-            if self.device.size <= self.device.format.minSize:
+            if (self.device.size < self.device.format.minSize or
+                (self.device.size == self.device.format.minSize and
+                 self.size > self.device.format.minSize)):
                 raise StorageError("failed to adjust device -- not enough free space in specified disks?")
 
     def _set_format(self):