merge changes made on other repos into ExportTree

Now when one repository has exported a tree, another repository can get
files from the export, after syncing.

There's a bug: While the database update works, somehow the database on
disk does not get updated, and so the database update is run the next
time, etc. Wasn't able to figure out why yet.

This commit was sponsored by Ole-Morten Duesund on Patreon.

Command/Export.hs

@@ -27,7 +27,6 @@ import Annex.LockFile
 import Logs.Location
 import Logs.Export
 import Database.Export
-import Remote.Helper.Export
 import Messages.Progress
 import Utility.Tmp
 
@@ -129,7 +128,7 @@ seek' o r = do
 					(\diff -> startUnexport r ea db (Git.DiffTree.file diff) (unexportboth diff))
 					oldtreesha new
 			updateExportTree db emptyTree new
-	liftIO $ recordDataSource db new
+	liftIO $ recordExportTreeCurrent db new
 
 	-- Waiting until now to record the export guarantees that,
 	-- if this export is interrupted, there are no files left over
@@ -312,3 +311,28 @@ cleanupRename ea db ek src dest = do
 	if exportDirectories src /= exportDirectories dest
 		then removeEmptyDirectories ea db src [asKey ek]
 		else return True
+
+-- | Remove empty directories from the export. Call after removing an
+-- exported file, and after calling removeExportLocation and flushing the
+-- database.
+removeEmptyDirectories :: ExportActions Annex -> ExportHandle -> ExportLocation -> [Key] -> Annex Bool
+removeEmptyDirectories ea db loc ks
+	| null (exportDirectories loc) = return True
+	| otherwise = case removeExportDirectory ea of
+		Nothing -> return True
+		Just removeexportdirectory -> do
+			ok <- allM (go removeexportdirectory) 
+				(reverse (exportDirectories loc))
+			unless ok $ liftIO $ do
+				-- Add location back to export database, 
+				-- so this is tried again next time.
+				forM_ ks $ \k ->
+					addExportedLocation db k loc
+				flushDbQueue db
+			return ok
+  where
+	go removeexportdirectory d = 
+		ifM (liftIO $ isExportDirectoryEmpty db d)
+			( removeexportdirectory d
+			, return True
+			)