sync: Fix parsing of gcrypt::rsync:// urls that use a relative path

Such an url is not valid; parseURI will fail on it. But git-annex doesn't
actually need to parse the url, because all it needs to do to support
syncing with it is know that it's not a local path, and use git pull and
push.

(Note that there is no good reason for the user to use such an url. An
absolute url is valid and I patched git-remote-gcrypt to support them
years ago. Still, users gonna do anything that tools allow, and
git-remote-gcrypt still supports them.)

Sponsored-by: Jack Hill on Patreon

Git/GCrypt.hs

@@ -55,7 +55,15 @@ encryptedRemote baserepo = go
 			    -- allows them); need to de-escape any such
 			    -- to get back the path to the repository.
 			    l' = Network.URI.unEscapeString l
-			in fromRemoteLocation l' baserepo
+			    -- gcrypt supports relative urls for rsync 
+			    -- like "rsync://host:relative/path"
+			    -- but that does not parse as a valid url
+			    -- (while the absolute urls it supports are
+			    -- valid). 
+			    -- In order to support it, force treating it as
+			    -- an url.
+			    knownurl = "rsync://" `isPrefixOf` l'
+			in fromRemoteLocation l' knownurl baserepo
 		| otherwise = notencrypted
 
 	notencrypted = giveup "not a gcrypt encrypted repository"