move --to: Better behavior when system is completely out of disk space; drop content from disk before writing location log.

I noticed move --to failing when there was no disk space. The file was sent
to the remote, but it crashed before it could be dropped locally. This
could fix that.

CHANGELOG

@@ -18,6 +18,8 @@ git-annex (6.20160528) UNRELEASED; urgency=medium
   * remotedaemon: Fixed support for notifications of changes to gcrypt
     remotes, which was never tested and didn't quite work before.
   * list: Do not include dead repositories.
+  * move --to: Better behavior when system is completely out of disk space;
+    drop content from disk before writing location log.
 
  -- Joey Hess <id@joeyh.name>  Fri, 27 May 2016 13:12:48 -0400
 

Command/Move.hs

@@ -113,23 +113,29 @@ toPerform dest move key afile fastcheck isthere =
 				upload (Remote.uuid dest) key afile noRetry noObserver $
 					Remote.storeKey dest key afile
 			if ok
-				then do
+				then finish $
 					Remote.logStatus dest key InfoPresent
-					finish
 				else do
 					when fastcheck $
 						warning "This could have failed because --fast is enabled."
 					stop
-		Right True -> do
+		Right True -> finish $
 			unlessM (expectedPresent dest key) $
 				Remote.logStatus dest key InfoPresent
-			finish
   where
-	finish
+	finish :: Annex () -> CommandPerform
+	finish setpresentremote
 		| move = lockContentForRemoval key $ \contentlock -> do
+			-- Drop content before updating location logs,
+			-- in case disk space is very low this frees up
+			-- space before writing data to disk.
 			removeAnnex contentlock
-			next $ Command.Drop.cleanupLocal key
-		| otherwise = next $ return True
+			next $ do
+				setpresentremote
+				Command.Drop.cleanupLocal key
+		| otherwise = next $ do
+			setpresentremote
+			return True
 
 {- Moves (or copies) the content of an annexed file from a remote
  - to the current repository.