copy: avoid updating location log when no copy is performed

git annex copy --to remote often does not need to copy a file,
but it was still updating the location log in this case.

Command/Move.hs

@@ -92,15 +92,16 @@ toPerform dest move key file = moveLock move key $ do
 			ok <- upload (Remote.uuid dest) key (Just file) noRetry $
 				Remote.storeKey dest key (Just file)
 			if ok
-				then finish
+				then finish True
 				else do
 					when fastcheck $
 						warning "This could have failed because --fast is enabled."
 					stop
-		Right True -> finish
+		Right True -> finish False
 	where
-		finish = do
-			Remote.logStatus dest key InfoPresent
+		finish remotechanged = do
+			when remotechanged $
+				Remote.logStatus dest key InfoPresent
 			if move
 				then do
 					whenM (inAnnex key) $ removeAnnex key

debian/changelog

@@ -1,3 +1,9 @@
+git-annex (3.20120925) UNRELEASED; urgency=low
+
+  * copy: Avoid updating the location log when no copy is performed.
+
+ -- Joey Hess <joeyh@debian.org>  Mon, 24 Sep 2012 19:58:07 -0400
+
 git-annex (3.20120924) unstable; urgency=low
 
   * assistant: New command, a daemon which does everything watch does,