common: Turn on Nix store auto-optimization.

This makes sense especially on tishtushi where disk space is sparse, but
also helps especially when testing/working on Nix expressions.

Motivated by a message from @wmertens:

http://lists.science.uu.nl/pipermail/nix-dev/2015-February/016180.html

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/common.nix b/common.nix
index 4d69f654..9d0d1cbc 100644
--- a/common.nix
+++ b/common.nix
@@ -9,6 +9,7 @@
     readOnlyStore = true;
     extraOptions = ''
       build-cores = 0
+      auto-optimise-store = true
     '';
   };