leave export logged as incomplete if initial renames fail

This way, the temp files that might be left due to failure will be
cleaned up next time.

Also, nub the list of incomplete exports to avoid repeatedly adding the
same tree to it when running export repeatedly when it's failing.

This commit was supported by the NSF-funded DataLad project.

Command/Export.hs

@@ -10,6 +10,7 @@
 module Command.Export where
 
 import Command
+import qualified Annex
 import qualified Git
 import qualified Git.DiffTree
 import qualified Git.LsTree
@@ -144,10 +145,12 @@ seek o = do
 	-- Waiting until now to record the export guarantees that,
 	-- if this export is interrupted, there are no files left over
 	-- from a previous export, that are not part of this export.
-	recordExport (uuid r) $ ExportChange
-		{ oldTreeish = map exportedTreeish old
-		, newTreeish = new
-		}
+	c <- Annex.getState Annex.errcounter
+	when (c == 0) $
+		recordExport (uuid r) $ ExportChange
+			{ oldTreeish = map exportedTreeish old
+			, newTreeish = new
+			}
 
 	-- Export everything that is not yet exported.
 	(l, cleanup') <- inRepo $ Git.LsTree.lsTree new

Logs/Export.hs

@@ -84,7 +84,7 @@ recordExportBeginning remoteuuid newtree = do
 		. M.lookup u . simpleMap 
 		. parseLogNew parseExportLog
 		<$> Annex.Branch.get exportLog
-	let new = old { incompleteExportedTreeish = newtree:incompleteExportedTreeish old }
+	let new = old { incompleteExportedTreeish = nub (newtree:incompleteExportedTreeish old) }
 	Annex.Branch.change exportLog $
 		showLogNew formatExportLog 
 			. changeLog c u (ExportLog new remoteuuid)