complete the magic wormhole pairin appid transition

Started in 2017 in commit 3fe9d99f24.
Starting tomorrow, all versions of git-annex since then will provide
an appid, and so it will no longer be necessary to check the date.

Sponsored-by: Nicholas Golder-Manning on Patreon

Command/P2P.hs

@@ -29,7 +29,6 @@ import qualified Utility.MagicWormhole as Wormhole
 
 import Control.Concurrent.Async
 import qualified Data.Text as T
-import Data.Time.Clock.POSIX
 
 cmd :: Command
 cmd = command "p2p" SectionSetup
@@ -233,30 +232,11 @@ wormholePairing remotename ouraddrs ui = do
 		void $ liftIO $ async $ ui observer producer
 		-- Provide an appid to magic wormhole, to avoid using
 		-- the same channels that other wormhole users use.
-		--
+		let appid = Wormhole.appId "git-annex.branchable.com/p2p-setup"
-		-- Since a version of git-annex that did not provide an
-		-- appid is shipping in Debian 9, and having one side
-		-- provide an appid while the other does not will make
-		-- wormhole fail, this is deferred until 2021-12-31.
-		-- After that point, all git-annex's should have been
-		-- upgraded to include this code, and they will start
-		-- providing an appid.
-		--
-		-- This assumes reasonably good client clocks. If the clock
-		-- is completely wrong, it won't use the appid at that
-		-- point, and pairing will fail. On 2021-12-31, minor clock
-		-- skew may also cause transient problems.
-		--
-		-- After 2021-12-31, this can be changed to simply
-		-- always provide the appid.
-		now <- liftIO getPOSIXTime
-		let wormholeparams = if now < 1640950000
-			then []
-			else Wormhole.appId "git-annex.branchable.com/p2p-setup"
 		(sendres, recvres) <- liftIO $
-			Wormhole.sendFile sendf observer wormholeparams
+			Wormhole.sendFile sendf observer appid
 				`concurrently`
-			Wormhole.receiveFile recvf producer wormholeparams
+			Wormhole.receiveFile recvf producer appid
 		liftIO $ removeWhenExistsWith R.removeLink (toRawFilePath sendf)
 		if sendres /= True
 			then return SendFailed