cros_portage_upgrade: disable the unittests

While cros_portage_upgrade is temporarily neutered, disable its unittest
to avoid failing the builds.

BUG=chromium:858925 chromium:859031
TEST=Tryjob

Change-Id: I49641b2b58e95aa41021766017e52e4437daaf53
Reviewed-on: https://chromium-review.googlesource.com/1120184
Trybot-Ready: Vincent Palatin <vpalatin@chromium.org>
Tested-by: Vincent Palatin <vpalatin@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Nicolas Norvez <norvez@chromium.org>
Commit-Queue: Vincent Palatin <vpalatin@chromium.org>
(cherry picked from commit e33bdbe1d4a1466d2b4cd66156b4b71c95d5c3d3)
Reviewed-on: https://chromium-review.googlesource.com/1137753
Reviewed-by: Bob Moragues <moragues@chromium.org>
Commit-Queue: Bob Moragues <moragues@chromium.org>
Tested-by: Bob Moragues <moragues@chromium.org>
diff --git a/cbuildbot/run_tests.py b/cbuildbot/run_tests.py
index 52c6d97..14df615 100644
--- a/cbuildbot/run_tests.py
+++ b/cbuildbot/run_tests.py
@@ -88,7 +88,7 @@
     'scripts/cros_mark_as_stable_unittest': INSIDE,
     'scripts/cros_mark_chrome_as_stable_unittest': INSIDE,
     'scripts/sync_package_status_unittest': INSIDE,
-    'scripts/cros_portage_upgrade_unittest': INSIDE,
+    'scripts/cros_portage_upgrade_unittest': SKIP,
     'scripts/dep_tracker_unittest': INSIDE,
     'scripts/test_image_unittest': INSIDE,
     'scripts/upload_package_status_unittest': INSIDE,