setup_venv: Clean up VENV_DEPENDENCIES using parsed lsb_release.

This is mostly a cleanup, but it should also save 50ms in the runtime
of create-production-venv.

scripts/lib/create-production-venv

@@ -15,11 +15,6 @@ parser = argparse.ArgumentParser(description="Create a production virtualenv wit
 parser.add_argument("deploy_path")
 args = parser.parse_args()
 
-codename = subprocess_text_output(["lsb_release", "-cs"])
-if codename != "trusty":
-    # Workaround for the fact that trusty has a different package name here.
-    VENV_DEPENDENCIES.append("virtualenv")
-
 # install dependencies for setting up the virtualenv
 run(["apt-get", "-y", "install"] + VENV_DEPENDENCIES)
 

scripts/lib/setup_venv.py

@@ -1,7 +1,7 @@
 
 import os
 import subprocess
-from scripts.lib.zulip_tools import run, ENDC, WARNING
+from scripts.lib.zulip_tools import run, ENDC, WARNING, parse_lsb_release
 from scripts.lib.hash_reqs import expand_reqs
 
 ZULIP_PATH = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
@@ -37,6 +37,12 @@ VENV_DEPENDENCIES = [
     "libpq-dev",            # Needed by psycopg2
 ]
 
+codename = parse_lsb_release()["DISTRIB_CODENAME"]
+
+if codename != "trusty":
+    # Workaround for the fact that trusty has a different package name here.
+    VENV_DEPENDENCIES.append("virtualenv")
+
 THUMBOR_VENV_DEPENDENCIES = [
     "libcurl4-openssl-dev",
     "libjpeg-dev",

tools/lib/provision.py

@@ -143,10 +143,6 @@ APT_DEPENDENCIES = {
         "postgresql-9.6",
         "postgresql-9.6-tsearch-extras",
         "postgresql-9.6-pgroonga",
-        # Technically, this should be in VENV_DEPENDENCIES, but it
-        # doesn't exist in trusty and we don't have a conditional on
-        # platform there.
-        "virtualenv",
     ],
     "trusty": UBUNTU_COMMON_APT_DEPENDENCIES + [
         "postgresql-9.3",
@@ -157,13 +153,11 @@ APT_DEPENDENCIES = {
         "postgresql-9.5",
         "postgresql-9.5-tsearch-extras",
         "postgresql-9.5-pgroonga",
-        "virtualenv",  # see comment on stretch
     ],
     "bionic": UBUNTU_COMMON_APT_DEPENDENCIES + [
         "postgresql-10",
         "postgresql-10-pgroonga",
         "postgresql-10-tsearch-extras",
-        "virtualenv",  # see comment on stretch
     ],
 }