[stable-only] Cap virtualenv for py37stable/train

py37 test started to fail with latest virtualenv (20.16.4) as it
bundles setuptools 65.3.0, which causes installation problems under
py37. (Note: with py38 the problem does not occur).

This patch sets virtualenv<20.16.4 to unblock the gate as
virtualenv 20.16.3 bundles setuptools 63.4.1, with which py37 gate
works well.

Conflicts:
  tox.ini

NOTE(elod.illes): conflict is caused by tox.ini cleanup patch, that was
  added in ussuri: I45981d5e80ab8ea03176ce08e119556fec078a37

Change-Id: I4c60766ea0daedf06023902a73b007c35f82de85
(cherry picked from commit ee7f2a8725094c3e88f6a10792bd34fb40b48276)

1 files changed, 4 insertions, 0 deletions

diff --git a/tox.ini b/tox.ini
index 9e3a960..38708ba 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,10 @@
 [tox]
 minversion = 2.0
 envlist = py27,py37,pep8
+# Pin setuptools via virtualenv as latest virtualenv pulls in 65.3.0
+# version of setuptools for py37, which causes installation problems
+# (virtualenv 20.16.3 uses setuptools 63.4.1).
+requires = virtualenv<20.16.4
 
 [testenv]
 install_command = pip install {opts} {packages}