bare cleanup

Command/Add.hs

@@ -29,7 +29,7 @@ seek = [withFilesNotInGit start, withFilesUnlocked start]
  - moving it into the annex directory and setting up the symlink pointing
  - to its content. -}
 start :: BackendFile -> CommandStart
-start p@(_, file) = notAnnexed file $ do
+start p@(_, file) = notBareRepo $ notAnnexed file $ do
 	s <- liftIO $ getSymbolicLinkStatus file
 	if isSymbolicLink s || not (isRegularFile s)
 		then stop

Command/AddUrl.hs

@@ -26,7 +26,7 @@ seek :: [CommandSeek]
 seek = [withStrings start]
 
 start :: String -> CommandStart
-start s = do
+start s = notBareRepo $ do
 	let u = parseURI s
 	case u of
 		Nothing -> error $ "bad url " ++ s

doc/bare_repositories.mdwn

@@ -16,3 +16,5 @@ as non-bare repositories. Except for these caveats:
   checkouts.
 * `git annex unused` in a bare repository only knows about keys used in
   branches that have been pushed to the bare repository. So use it with care..
+* Commands that need a work tree, like `git annex add` won't work in a bare
+  repository, of course.