venvlib: use --never-download & extra verbose output

Just for sanity sake, add the --never-download flag to make sure we
never accidentally start fetching from the network.  This has existed
since virtualenv 1.7, so older versions are safe.

To help with debugging, run with extra verbose flags.  This output
does not add any real overhead, and we save it to a logfile, so users
would never see it unless we crashed (at which point, the output is
pretty helpful).  Plus, this command is run once to generate a cache,
and not after that, so a single chatty command per-cache is OK.

TEST=CQ passes

Change-Id: Ia55076b8fe9e11a4f7637615033a5a7986ee5739
Reviewed-by: Chris McDonald <>
Commit-Queue: Mike Frysinger <>
Tested-by: Mike Frysinger <>
diff --git a/venv/cros_venv/ b/venv/cros_venv/
index 30d1bc5..436d208 100644
--- a/venv/cros_venv/
+++ b/venv/cros_venv/
@@ -247,7 +247,8 @@
     env.pop('VIRTUALENV_ALWAYS_COPY', None)
     command = [_VIRTUALENV_COMMAND, venvdir, '-p', sys.executable,
-               '--extra-search-dir', _PACKAGE_DIR, '--clear']
+               '--extra-search-dir', _PACKAGE_DIR, '--clear',
+               '--never-download', '-vvvvv']
     # TODO(ayatane): Ubuntu Precise ships with virtualenv 1.7, which
     # requires specifying --setuptools, else distribute is used
     # (distribute is deprecated).  virtualenv after 1.10 uses setuptools