compute remote: get input files from other remotes

This needed some refactoring to avoid cycles, since Remote.Compute
cannot import Remote.List. Instead, it uses Annex.remotes. Which must be
populated by something else, but we know it has been, because something
is using Remote.Compute, which it must have found in the remote list,
which populates that.

In Remote.Compute, keyPossibilities' is called with all loggedLocations,
without the trustExclude DeadTrusted that keyLocations does. There is
another cycle there. This may be a problem if a dead repository is still
a remote.

This is missing cycle prevention, and it's certianly possible to make 2
files in the compute remote co-depend on one-another. Hopefully not in a
real world situation, but it an attacker could certainly do it. Cycle
prevention will need to be added to this.

Remote.hs

@@ -319,22 +319,11 @@ remoteFromUUID u = ifM ((==) u <$> getUUID)
 		remotesChanged
 		findinmap
 
-{- Filters a list of remotes to ones that have the listed uuids. -}
-remotesWithUUID :: [Remote] -> [UUID] -> [Remote]
-remotesWithUUID rs us = filter (\r -> uuid r `elem` us) rs
-
-{- Filters a list of remotes to ones that do not have the listed uuids. -}
-remotesWithoutUUID :: [Remote] -> [UUID] -> [Remote]
-remotesWithoutUUID rs us = filter (\r -> uuid r `notElem` us) rs
-
 {- List of repository UUIDs that the location log indicates may have a key.
  - Dead repositories are excluded. -}
 keyLocations :: Key -> Annex [UUID]
 keyLocations key = trustExclude DeadTrusted =<< loggedLocations key
 
-{- Whether to include remotes that have annex-ignore set. -}
-newtype IncludeIgnored = IncludeIgnored Bool
-
 {- Cost ordered lists of remotes that the location log indicates
  - may have a key.
  -
@@ -342,33 +331,16 @@ newtype IncludeIgnored = IncludeIgnored Bool
  -}
 keyPossibilities :: IncludeIgnored -> Key -> Annex [Remote]
 keyPossibilities ii key = do
-	u <- getUUID
-	-- uuids of all remotes that are recorded to have the key
-	locations <- filter (/= u) <$> keyLocations key
-	speclocations <- map uuid
-		. filter (remoteAnnexSpeculatePresent . gitconfig)
-		<$> remoteList
-	-- there are unlikely to be many speclocations, so building a Set
-	-- is not worth the expense
-	let locations' = speclocations ++ filter (`notElem` speclocations) locations
-	fst <$> remoteLocations ii locations' []
+	locations <- keyLocations key
+	keyPossibilities' ii key locations =<< remoteList
 
 {- Given a list of locations of a key, and a list of all
  - trusted repositories, generates a cost-ordered list of
  - remotes that contain the key, and a list of trusted locations of the key.
  -}
 remoteLocations :: IncludeIgnored -> [UUID] -> [UUID] -> Annex ([Remote], [UUID])
-remoteLocations (IncludeIgnored ii) locations trusted = do
-	let validtrustedlocations = nub locations `intersect` trusted
-
-	-- remotes that match uuids that have the key
-	allremotes <- remoteList 
-		>>= if not ii
-			then filterM (not <$$> liftIO . getDynamicConfig . remoteAnnexIgnore . gitconfig)
-			else return
-	let validremotes = remotesWithUUID allremotes locations
-
-	return (sortBy (comparing cost) validremotes, validtrustedlocations)
+remoteLocations ii locations trusted = 
+	remoteLocations' ii locations trusted =<< remoteList
 
 {- Displays known locations of a key and helps the user take action
  - to make them accessible. -}