smudge: check for known annexed inodes before checking annex.largefiles

smudge: Fix a case where an unlocked annexed file that annex.largefiles
does not match could get its unchanged content checked into git, due to git
running the smudge filter unecessarily.

When the file has the same inodecache as an already annexed file,
we can assume that the user is not intending to change how it's stored in
git.

Note that checkunchangedgitfile already handled the inverse case, where the
file was added to git previously. That goes further and actually sha1
hashes the new file and checks if it's the same hash in the index.

It would be possible to generate a key for the file and see if it's the
same as the old key, however that could be considerably more expensive than
sha1 of a small file is, and it is not necessary for the case I have, at
least, where the file is not modified or touched, and so its inode will
match the cache.

git-annex add was changed, when adding a small file, to remove the inode
cache for it. This is necessary to keep the recipe in
doc/tips/largefiles.mdwn for converting from annex to git working.
It also avoids bugs/case_where_using_pathspec_with_git-commit_leaves_s.mdwn
which the earlier try at this change introduced.

Command/Add.hs

@@ -22,6 +22,8 @@ import Git.FilePath
 import Config.GitConfig
 import Config.Smudge
 import Utility.OptParse
+import Utility.InodeCache
+import Annex.InodeSentinal
 import qualified Utility.RawFilePath as R
 
 cmd :: Command
@@ -129,13 +131,24 @@ data SmallOrLarge = Small | Large
 addFile :: SmallOrLarge -> CheckGitIgnore -> RawFilePath -> Annex Bool
 addFile smallorlarge ci file = do
 	ps <- gitAddParams ci
+	cps <- case smallorlarge of
+		-- In case the file is being converted from an annexed file
+		-- to be stored in git, remove the cached inode, so that
+		-- if the smudge clean filter later runs on the file,
+		-- it will not remember it was annexed.
+		--
+		-- The use of bypassSmudgeConfig prevents the smudge
+		-- filter from being run. So the changes to the database
+		-- can be queued up and not flushed to disk immediately.
+		Small -> do
+			withTSDelta (liftIO . genInodeCache file) >>= \case
+				Just ic -> Database.Keys.removeInodeCache ic
+				Nothing -> return ()
+			return bypassSmudgeConfig
+		Large -> return []
 	Annex.Queue.addCommand cps "add" (ps++[Param "--"])
 		[fromRawFilePath file]
 	return True
-  where
-	cps = case smallorlarge of
-		Large -> []
-		Small -> bypassSmudgeConfig
 
 start :: AddOptions -> SeekInput -> RawFilePath -> AddUnlockedMatcher -> CommandStart
 start o si file addunlockedmatcher = do