fix install of debootstrap from source

src/Propellor/Property/Debootstrap.hs

@@ -2,7 +2,9 @@ module Propellor.Property.Debootstrap (
 	Url,
 	DebootstrapConfig(..),
 	built,
+	built',
 	installed,
+	sourceInstall,
 	programPath,
 ) where
 
@@ -54,11 +56,14 @@ toParams (c1 :+ c2) = toParams c1 <> toParams c2
 -- Note that reverting this property does not stop any processes
 -- currently running in the chroot.
 built :: FilePath -> System -> DebootstrapConfig -> RevertableProperty
-built target system@(System _ arch) config =
+built = built' (toProp installed)
+
+built' :: Property -> FilePath -> System -> DebootstrapConfig -> RevertableProperty
+built' installprop target system@(System _ arch) config =
 	RevertableProperty setup teardown
   where
 	setup = check (unpopulated target <||> ispartial) setupprop
-		`requires` toProp installed
+		`requires` installprop
 	
 	teardown = check (not <$> unpopulated target) teardownprop
 	

src/Propellor/Property/OS.hs

@@ -78,7 +78,10 @@ cleanInstallOnce confirmation = check (not <$> doesFileExist flagfile) $
 		(Just u@(System (Ubuntu _) _)) -> debootstrap u
 		_ -> error "os is not declared to be Debian or Ubuntu"
 	debootstrap targetos = ensureProperty $ toProp $
-		Debootstrap.built newOSDir targetos Debootstrap.DefaultConfig
+		-- Ignore the os setting, and install debootstrap from
+		-- source, since we don't know what OS we're running in yet.
+		Debootstrap.built' Debootstrap.sourceInstall
+			newOSDir targetos Debootstrap.DefaultConfig
 	
 	flipped = property (newOSDir ++ " moved into place") $ liftIO $ do
 		-- First, unmount most mount points, lazily, so