close send side of password pipe on exec

This avoids a hang approximately 1% of the time when running the test
suite on StatelessOpenPGP.

Since I've not seen git-annex hang when running git like that, I guess
git probably does something that avoids hanging similarly. Still, fixed
the same problem in Utility.Gpg too.

Sponsored-by: Kevin Mueller on Patreon

Utility/Gpg.hs

@@ -163,6 +163,7 @@ feedRead cmd params passphrase feeder reader = do
 	let setup = liftIO $ do
 		-- pipe the passphrase into gpg on a fd
 		(frompipe, topipe) <- System.Posix.IO.createPipe
+		setFdOption topipe CloseOnExec True
 		toh <- fdToHandle topipe
 		t <- async $ do
 			B.hPutStr toh (passphrase <> "\n")

Utility/StatelessOpenPGP.hs

@@ -133,6 +133,7 @@ feedRead cmd subcmd params password emptydirectory feeder reader = do
 	let setup = liftIO $ do
 		-- pipe the passphrase in on a fd
 		(frompipe, topipe) <- System.Posix.IO.createPipe
+		setFdOption topipe CloseOnExec True
 		toh <- fdToHandle topipe
 		t <- async $ do
 			B.hPutStr toh (password <> "\n")