fix a place where the inode cache could potentially have gotten stale

When git-annex lock repopulates the object file by copying an associated
file that still has its content, it negected to update the inode cache.

I was not able to actually get this code to successfully repopulate the
object file; the associated file gets replaced with a dangling pointer
before unlock is able to do that. (By what I'm not sure..
reconcileStaged?) Which might be itself a bug, but
anyway this makes me doubtful that this was really leading to a stale
inode cache. Still, in case there is some situation in which it does
work, fixed it to update the inode cache.

Command/Lock.hs

@@ -91,8 +91,10 @@ perform file key = do
 		liftIO $ removeWhenExistsWith R.removeLink obj
 		case mfile of
 			Just unmodified ->
-				unlessM (checkedCopyFile key unmodified obj Nothing)
-					lostcontent
+				ifM (checkedCopyFile key unmodified obj Nothing)
+					( Database.Keys.storeInodeCaches key [obj]
+					, lostcontent
+					)
 			Nothing -> lostcontent
 
 	lostcontent = logStatus key InfoMissing