webapp: avoid overwriting remote configs when enabling it

Avoid stomping on existing group and preferred content settings
when enabling or combining with an already existing remote.

Two level fix. First, use defaultStandardGroup rather than
setStandardGroup, so if there is an existing configuration in the git-annex
branch, it's not overwritten.

To handle pre-existing ssh remotes (including gcrypt), a second level is
needed, because before syncing with the remote, it's configuration won't be
available locally. (And syncing could take a long time.) So, in this case,
keep track of whether the remote is being created or enabled, and only set
configs when creating it.

This commit was sponsored by Anders Lannerback.

Logs/PreferredContent.hs

@@ -18,6 +18,7 @@ module Logs.PreferredContent (
 	groupPreferredContentMapRaw,
 	checkPreferredContentExpression,
 	setStandardGroup,
+	defaultStandardGroup,
 	preferredRequiredMapsLoad,
 ) where
 
@@ -133,10 +134,20 @@ checkPreferredContentExpression expr = case parsedToMatcher tokens of
 	tokens = exprParser matchAll matchAll emptyGroupMap M.empty Nothing expr
 
 {- Puts a UUID in a standard group, and sets its preferred content to use
- - the standard expression for that group, unless something is already set. -}
+ - the standard expression for that group (unless preferred content is
+ - already set). -}
 setStandardGroup :: UUID -> StandardGroup -> Annex ()
 setStandardGroup u g = do
 	groupSet u $ S.singleton $ fromStandardGroup g
-	m <- preferredContentMap
-	unless (isJust $ M.lookup u m) $
+	unlessM (isJust . M.lookup u <$> preferredContentMap) $
 		preferredContentSet u "standard"
+
+{- Avoids overwriting the UUID's standard group or preferred content
+ - when it's already been configured. -}
+defaultStandardGroup :: UUID -> StandardGroup -> Annex ()
+defaultStandardGroup u g = 
+	unlessM (hasgroup <||> haspc) $
+		setStandardGroup u g
+  where
+	hasgroup = not . S.null <$> lookupGroups u
+	haspc = isJust . M.lookup u <$> preferredContentMap