when reading configs of local repos, first initializeSafe

This auto-generates a uuid if the local repo does not already have one.

Init.hs

@@ -5,7 +5,11 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-module Init (initialize, uninitialize) where
+module Init (
+	initialize,
+	initializeSafe,
+	uninitialize
+) where
 
 import Control.Monad.State (liftIO)
 import Control.Monad (unless)
@@ -34,6 +38,17 @@ uninitialize = do
 	g <- Annex.gitRepo
 	gitPreCommitHookUnWrite g
 
+{- Call to automatically initialize if there is already a git-annex
+   branch from somewhere. Otherwise, require a manual init
+   to avoid git-annex accidentially being run in git
+   repos that did not intend to use it. -}
+initializeSafe :: Annex ()
+initializeSafe = do
+	annexed <- Branch.hasSomeBranch
+	if annexed
+		then initialize
+		else error "First run: git-annex init"
+
 {- set up a git pre-commit hook, if one is not already present -}
 gitPreCommitHookWrite :: Git.Repo -> Annex ()
 gitPreCommitHookWrite repo = do