Chroot builds: Provide world-readable /nix/store

This was causing NixOS VM tests to fail mysteriously since
5ce50cd99e740d0d0f18c30327ae687be9356553. Nscd could (sometimes) no
longer read /etc/hosts:

open("/etc/hosts", O_RDONLY|O_CLOEXEC) = -1 EACCES (Permission denied)

Probably there was some wacky interaction between the guest kernel and
the 9pfs implementation in QEMU.

1 files changed, 1 insertions, 1 deletions

diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc
index 9a69a795e8..f3a4a459eb 100644
--- a/nix/libstore/build.cc
+++ b/nix/libstore/build.cc
@@ -1826,7 +1826,7 @@ void DerivationGoal::startBuilder()
            build user. */
         Path chrootStoreDir = chrootRootDir + settings.nixStore;
         createDirs(chrootStoreDir);
-        chmod_(chrootStoreDir, 0730);
+        chmod_(chrootStoreDir, 0735);
 
         if (chown(chrootStoreDir.c_str(), 0, buildUser.getGID()) == -1)
             throw SysError(format("cannot change ownership of ‘%1%’") % chrootStoreDir);