Fix a potential failure to parse git config

Git has an obnoxious special case in git config, a line "foo" is the same
as "foo = true". That means there is no way to examine the output of
git config and tell if it was run with --null or not, since a "foo"
in the first line could be such a boolean, or could be followed by its
value on the next line if --null were used.

So, rather than trying to do such a detection, track the style of config
at all the points where it's generated.

CmdLine/GitAnnex/Options.hs

@@ -96,7 +96,7 @@ gitAnnexGlobalOptions = commonGlobalOptions ++
 	setgitconfig v = Annex.adjustGitRepo $ \r -> 
 		if Param v `elem` gitGlobalOpts r
 			then return r
-			else Git.Config.store (encodeBS' v) $ 
+			else Git.Config.store (encodeBS' v) Git.Config.ConfigList $ 
 				r { gitGlobalOpts = gitGlobalOpts r ++ [Param "-c", Param v] }
 	setdesktopnotify v = Annex.changeState $ \s -> s { Annex.desktopnotify = Annex.desktopnotify s <> v }