fix nested exception bug

Fix reversion introduced in version 6.20180316 that caused git-annex to
stop processing files when unable to contact a ssh remote.

The bug was not in any of the changed lines, but this one in inAnnex:

P2PHelper.checkpresent (Ssh.runProto rmt connpool (cantCheck rmt) fallback) key

cantCheck throws an exception, but that parameter to runProto expects a
value, which it returns. So, inAnnex is returning a Bool containing an
exception. This defeats the usual checks for checkPresent throwing an
exception, crashing git-annex.

Fixed by making runProto take an `Annex a` instead of an `a`, so
passing cantCheck to it doesn't nest exceptions.

This commit was sponsored by andrea rota.

CHANGELOG

@@ -8,6 +8,8 @@ git-annex (6.20180627) UNRELEASED; urgency=medium
     still check if the url is one that it supports, and fail downloading
     it, instead of downloading the raw web page.
   * git-annex.cabal: Fix network version.
+  * Fix reversion introduced in version 6.20180316 that caused git-annex to
+    stop processing files when unable to contact a ssh remote.
 
  -- Joey Hess <id@joeyh.name>  Fri, 22 Jun 2018 10:36:22 -0400
 

Remote/Git.hs

@@ -395,7 +395,7 @@ dropKey' repo r (State connpool duc _) key
 	| Git.repoIsHttp repo = giveup "dropping from http remote not supported"
 	| otherwise = commitOnCleanup repo r $ do
 		let fallback = Ssh.dropKey repo key
-		P2PHelper.remove (Ssh.runProto r connpool False fallback) key
+		P2PHelper.remove (Ssh.runProto r connpool (return False) fallback) key
 
 lockKey :: Remote -> State -> Key -> (VerifiedCopy -> Annex r) -> Annex r
 lockKey r st key callback = do
@@ -493,7 +493,7 @@ copyFromRemote'' repo forcersync r (State connpool _ _) key file dest meterupdat
 	| Git.repoIsSsh repo = if forcersync
 		then fallback meterupdate
 		else P2PHelper.retrieve
-			(\p -> Ssh.runProto r connpool (False, UnVerified) (fallback p))
+			(\p -> Ssh.runProto r connpool (return (False, UnVerified)) (fallback p))
 			key file dest meterupdate
 	| otherwise = giveup "copying from non-ssh, non-http remote not supported"
   where
@@ -605,7 +605,7 @@ copyToRemote' repo r (State connpool duc _) key file meterupdate
 		)
 	| Git.repoIsSsh repo = commitOnCleanup repo r $
 		P2PHelper.store
-			(\p -> Ssh.runProto r connpool False (copyremotefallback p))
+			(\p -> Ssh.runProto r connpool (return False) (copyremotefallback p))
 			key file meterupdate
 		
 	| otherwise = giveup "copying to non-ssh repo not supported"

Remote/Helper/Ssh.hs

@@ -321,8 +321,8 @@ newStderrHandler errh = do
 
 -- Runs a P2P Proto action on a remote when it supports that,
 -- otherwise the fallback action.
-runProto :: Remote -> P2PSshConnectionPool -> a -> Annex a -> P2P.Proto a -> Annex (Maybe a)
+runProto :: Remote -> P2PSshConnectionPool -> Annex a -> Annex a -> P2P.Proto a -> Annex (Maybe a)
-runProto r connpool bad fallback proto = Just <$>
+runProto r connpool badproto fallback proto = Just <$>
 	(getP2PSshConnection r connpool >>= maybe fallback go)
   where
 	go c = do
@@ -333,7 +333,7 @@ runProto r connpool bad fallback proto = Just <$>
 				return res
 			-- Running the proto failed, either due to a protocol
 			-- error or a network error.
-			Nothing -> return bad
+			Nothing -> badproto
 
 runProtoConn :: P2P.Proto a -> P2PSshConnection -> Annex (P2PSshConnection, Maybe a)
 runProtoConn _ P2P.ClosedConnection = return (P2P.ClosedConnection, Nothing)

doc/forum/sync_quits_after_first_non-successfull_remote/comment_1_dbca6ea763702a82ae7563722cdc7fab._comment

@@ -0,0 +1,11 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 1"""
+ date="2018-07-03T17:00:26Z"
+ content="""
+Thanks for reporting, I've reproduced and fixed the bug.
+
+Please file bugs in the bug tracker in the future,
+that will prevent me missing them or responding as slowly as I did with
+this one.
+"""]]