fix permissions on initial install

running installer as root allows some file ownership from the archive to be set as a user other than root

tljh/installer.py

@@ -1,15 +1,16 @@
-import sys
+import argparse
 import os
-import tljh.systemd as systemd
-import tljh.conda as conda
+import secrets
+import subprocess
+import sys
+import time
 from urllib.error import HTTPError
 from urllib.request import urlopen, URLError
-from tljh import user
-import secrets
-import argparse
-import time
+
 from ruamel.yaml import YAML
 
+from tljh import conda, systemd, user
+
 INSTALL_PREFIX = os.environ.get('TLJH_INSTALL_PREFIX', '/opt/tljh')
 HUB_ENV_PREFIX = os.path.join(INSTALL_PREFIX, 'hub')
 USER_ENV_PREFIX = os.path.join(INSTALL_PREFIX, 'user')
@@ -193,6 +194,9 @@ def main():
 
     ensure_usergroups()
     ensure_user_environment(args.user_requirements_txt_url)
+    # Weird setuptools issue creates a few world-writable metadata files.
+    # Fix it:
+    subprocess.check_call(["chmod", "-R", "o-w", os.path.join(HUB_ENV_PREFIX, "pkgs")])
 
     print("Setting up JupyterHub...")
     ensure_jupyterhub_package(HUB_ENV_PREFIX)