initremote: Prevent enabling encryption with exporttree=yes/importtree=yes

I do think this was a reversion, but I have not tracked back to what
version. While involving the remote config, it's not the same class of
problems that I kept having to chase down for a while after the remote
config parser reworking.

Remote/Helper/Encryptable.hs

@@ -20,6 +20,7 @@ module Remote.Helper.Encryptable (
 	cipherKey,
 	extractCipher,
 	isEncrypted,
+	encryptionIsEnabled,
 	describeEncryption,
 	encryptionField,
 	highRandomQualityField
@@ -282,6 +283,14 @@ extractCipher c = case (getRemoteConfigValue cipherField c,
 isEncrypted :: ParsedRemoteConfig -> Bool
 isEncrypted = isJust . extractCipher
 
+-- Check if encryption is enabled. This can be done before encryption
+-- is fully set up yet, so the cipher might not be present yet.
+encryptionIsEnabled :: ParsedRemoteConfig -> Bool
+encryptionIsEnabled c = case getRemoteConfigValue encryptionField c of
+	Nothing -> False
+	Just NoneEncryption -> False
+	Just _ -> True
+
 describeEncryption :: ParsedRemoteConfig -> String
 describeEncryption c = case extractCipher c of
 	Nothing -> "none"