Cause virtualenv to be installed into the mirror

Virtualenv is a key piece of our infrastructure and is essential to the
gating work that we do, but because nothing depends on it, it doesn't
wind up in our mirror.

Change-Id: I23486aed48e367e797beee8e01a6ddee193d4227
diff --git a/jeepyb/cmd/run_mirror.py b/jeepyb/cmd/run_mirror.py
index 70a89c9..dfc1800 100644
--- a/jeepyb/cmd/run_mirror.py
+++ b/jeepyb/cmd/run_mirror.py
@@ -223,6 +223,9 @@
                     out = self.run_command(upgrade_format %
                                            (pip, pip_cache_dir,
                                             build, "pip"))
+                    out = self.run_command(upgrade_format %
+                                           (pip, pip_cache_dir,
+                                            build, "virtualenv"))
                     if os.path.exists(build):
                         shutil.rmtree(build)
                     new_reqs = self.process_http_requirements(reqlist,