try harder to verify until at least one VerifiedCopyLock is obtained

This avoids a failure where eg, we start with RecentlyVerifiedCopies
for all remotes, and so didn't do any active verification, which is
required.

Also, dedup the list of VerifiedCopies when checking if we have enough,
in case 2 copies of a UUID slip in.

Annex/NumCopies.hs

@@ -77,7 +77,11 @@ getFileNumCopies' file = maybe getGlobalNumCopies (return . Just) =<< getattr
 
 {- Checks if numcopies are satisfied for a file by running a comparison
  - between the number of (not untrusted) copies that are
- - belived to exist, and the configured value. -}
+ - belived to exist, and the configured value.
+ -
+ - This is good enough for everything except dropping the file, which
+ - requires active verification of the copies.
+ -}
 numCopiesCheck :: FilePath -> Key -> (Int -> Int -> v) -> Annex v
 numCopiesCheck file key vs = do
 	have <- trustExclude UnTrusted =<< Remote.keyLocations key
@@ -89,14 +93,14 @@ numCopiesCheck' file vs have = do
 	return $ length have `vs` needed
 
 {- Verifies that enough copies of a key exist amoung the listed remotes,
- - priting an informative message if not.
+ - printing an informative message if not.
  -}
 verifyEnoughCopies 
 	:: String -- message to print when there are no known locations
 	-> Key
 	-> NumCopies
 	-> [UUID] -- repos to skip considering (generally untrusted remotes)
-	-> [VerifiedCopy] -- already known verifications
+	-> [VerifiedCopy] -- copies already verified to exist
 	-> [Remote] -- remotes to check to see if they have it
 	-> Annex Bool
 verifyEnoughCopies nolocmsg key need skip preverified tocheck = 
@@ -113,15 +117,13 @@ verifyEnoughCopies nolocmsg key need skip preverified tocheck =
 			if verifiedEnoughCopies need stillhave
 				then return True
 				else helper bad missing stillhave (r:rs)
-		| any (== u) (map toUUID have) = helper bad missing have rs
+		| any isFullVerification have = helper bad missing have rs
 		| otherwise = do
 			haskey <- Remote.hasKey r key
 			case haskey of
-				Right True  -> helper bad missing (mkVerifiedCopy RecentlyVerifiedCopy u : have) rs
+				Right True  -> helper bad missing (mkVerifiedCopy RecentlyVerifiedCopy r : have) rs
 				Left _      -> helper (r:bad) missing have rs
-				Right False -> helper bad (u:missing) have rs
-	   where
-		u = Remote.uuid r
+				Right False -> helper bad (Remote.uuid r:missing) have rs
 
 {- Check whether enough verification has been done of copies to allow
  - dropping content safely.
@@ -138,10 +140,11 @@ verifyEnoughCopies nolocmsg key need skip preverified tocheck =
 verifiedEnoughCopies :: NumCopies -> [VerifiedCopy] -> Bool
 verifiedEnoughCopies (NumCopies n) l
 	| n == 0 = True
-	| otherwise = length l >= n && any islock l
-  where
-	islock (VerifiedCopyLock _) = True
-	islock _ = False
+	| otherwise = length (deDupVerifiedCopies l) >= n && any isFullVerification l
+
+isFullVerification :: VerifiedCopy -> Bool
+isFullVerification (VerifiedCopyLock _) = True
+isFullVerification _ = False
 
 notEnoughCopies :: Key -> NumCopies -> [VerifiedCopy] -> [UUID] -> [Remote] -> String -> Annex ()
 notEnoughCopies key need have skip bad nolocmsg = do