make --in=here fast

Use the same optimisation for --in=here as has always been used for --in=.
rather than the slow code path that unncessarily queries the git-annex
branch.

It looks like when "here" got added as an alias for "." back in 2012, I
forgot about this place.

Also sped up some very unlikely ways of referring to the current
repository.

Note that, this could in some rare corner case cause a behavior
change, if the git-annex branch and inAnnex disagree about whether content
is present in the local repository. But --in=. already behaved
that way, and the truth on the ground should win also.

Limit.hs

@@ -110,15 +110,15 @@ matchMagic limitname _ _ Nothing _ =
 {- Adds a limit to skip files not believed to be present
  - in a specfied repository. Optionally on a prior date. -}
 addIn :: String -> Annex ()
-addIn s = addLimit =<< mk
+addIn s = do
+	u <- Remote.nameToUUID name
+	hereu <- getUUID
+	addLimit $ if u == hereu && null date
+		then use inhere
+		else use (inuuid u)
   where
 	(name, date) = separate (== '@') s
-	mk
-		| name == "." = if null date
-			then use inhere
-			else use . inuuid =<< getUUID
-		| otherwise = use . inuuid =<< Remote.nameToUUID name
-	use a = return $ Right $ \notpresent -> checkKey (a notpresent)
+	use a = Right $ checkKey . a
 	inuuid u notpresent key
 		| null date = do
 			us <- Remote.keyLocations key