Index: tox/_venv.py
===================================================================
--- tox-1.4.2/tox/_venv.py
+++ tox-1.4.2.orig/tox/_venv.py	2020-04-02 16:05:49.006344130 +0200
@@ -224,10 +224,6 @@
 
     def pip_install(self, args, indexserver=None, action=None):
         argv = ["pip", "install"] + self._commoninstallopts(indexserver)
-        if self.envconfig.downloadcache:
-            self.envconfig.downloadcache.ensure(dir=1)
-            argv.append("--download-cache=%s" %
-                self.envconfig.downloadcache)
         for x in ('PIP_RESPECT_VIRTUALENV', 'PIP_REQUIRE_VIRTUALENV'):
             try:
                 del os.environ[x]