assistant: Support repairing git remotes that are locally accessible

(eg, on removable drives)

gcrypt remotes are not yet handled.

This commit was sponsored by Sören Brunk.

Remote/Web.hs

@@ -57,6 +57,7 @@ gen r _ _ gc =
 		hasKeyCheap = False,
 		whereisKey = Just getUrls,
 		remoteFsck = Nothing,
+		repairRepo = Nothing,
 		config = M.empty,
 		gitconfig = gc,
 		localpath = Nothing,