Allow regular repository sync again

It's unrealistic to disallow it in a decentralized
repository environment, since the repositories
are too inter-dependent.

So we assume that images deriving from this one
will call 'cave sync' early in case they add
repositories.

Dockerfile

@@ -14,7 +14,3 @@ RUN /bootstrap.sh amd64 x86_64
 # update etc files... hope this doesn't screw up
 RUN eclectic config accept-all
 
-# don't allow regular sync, because we want to make sure
-# all images deriving from this one have the same state
-RUN sed -i -e 's|^sync|#sync|' /etc/paludis/repositories/*.conf
-

README.md

@@ -0,0 +1,5 @@
+# Docker exherbo
+
+If you derive from this image and add further exherbo repositories,
+you should make a complete `cave sync` as well to ensure
+consistent inter-repository-state.