Re-organise checking of persisted data so the failure paths bail out

of the function first.
Also bail out if there is no persisted ring, since persisted 'owned'
data isn't meaningful in that state.

ipam/allocator.go

@@ -901,28 +901,34 @@ func (alloc *Allocator) loadPersistedData() bool {
 		alloc.fatalf("Error loading persisted address data: %s", err)
 	}
 
-	if nameFound {
-		if checkPeerName == alloc.ourName {
-			if ringFound {
-				alloc.ring = persistedRing
-				alloc.space.UpdateRanges(alloc.ring.OwnedRanges())
-			}
-			if ownedFound {
-				alloc.owned = persistedOwned
-				for _, d := range alloc.owned {
-					for _, cidr := range d.Cidrs {
-						alloc.space.Claim(cidr.Addr)
-					}
-				}
-			}
-			return true
-		}
-		alloc.infof("Deleting persisted data for peername %s", checkPeerName)
+	overwritePersisted := func(fmt string, args ...interface{}) {
+		alloc.infof(fmt, args...)
 		alloc.persistRing()
 		alloc.persistOwned()
 	}
 
-	return false
+	if !nameFound || !ringFound {
+		overwritePersisted("No valid persisted data")
+		return false
+	}
+
+	if checkPeerName != alloc.ourName {
+		overwritePersisted("Deleting persisted data for peername %s", checkPeerName)
+		return false
+	}
+
+	alloc.ring = persistedRing
+	alloc.space.UpdateRanges(alloc.ring.OwnedRanges())
+
+	if ownedFound {
+		alloc.owned = persistedOwned
+		for _, d := range alloc.owned {
+			for _, cidr := range d.Cidrs {
+				alloc.space.Claim(cidr.Addr)
+			}
+		}
+	}
+	return true
 }
 
 func (alloc *Allocator) persistOwned() {