toolchain in docker-utils-0.1.7

- old
+ new

@@ -22,14 +22,19 @@
 toolchain_available = system 'docker', 'inspect', '-f', '{{.Id}}', toolchain_image, out: '/dev/null', err: '/dev/null'
 unless toolchain_available
   system 'docker', 'pull', toolchain_image
 end
 
+expunge_env_keys = [
+  'TMPDIR'
+]
+
 host_env_keys = ENV.keys
 container_env_keys = `docker inspect -f '{{.Config.Env}}' #{toolchain_image}`.chomp[1..-2].split(' ').map{ |pair| pair.split('=').first }
 
-share_env_keys = host_env_keys - container_env_keys
+share_env_keys = host_env_keys - container_env_keys - expunge_env_keys
 share_env_args = share_env_keys.map{ |k| ['-e', k] }.flatten
+
 
 interaction_args = ($stdin.tty? && $stdout.tty?) ? ['-i', '-t'] : []
 
 docker_bin_path = `which docker`.chomp
 Kernel.exec docker_bin_path, 'run', '--rm',