Stop configuring install_command in tox.

It turns out that this is the the default value provided by tox:

https://tox.readthedocs.io/en/latest/config.html#conf-install_command

So we can remove the line and simply use the default value.

Change-Id: I2e440cfe22097256cff2dc019458e58c2616df27
Co-Authored-By: tushargite96 <tushargite96@gmail.com>

manifests/agents/ml2/ovs.pp

@@ -336,12 +336,17 @@ class neutron::agents::ml2::ovs (
     # (The bridge names can be nearly anything, they just have to match between
     # mappings and uplinks; they're what the OVS switches will get named.)
 
+    $bridge_mappings_real = $bridge_mappings ? {
+      String  => $bridge_mappings.split(',').strip(),
+      default => $bridge_mappings,
+    }
+
     # Set config for bridges that we're going to create
     # The OVS neutron plugin will talk in terms of the networks in the bridge_mappings
-    $br_map_str = join(any2array($bridge_mappings), ',')
     neutron_agent_ovs {
-      'ovs/bridge_mappings': value => $br_map_str;
+      'ovs/bridge_mappings': value => join(any2array($bridge_mappings_real), ',');
     }
+
     if ($manage_vswitch) {
       neutron::plugins::ovs::bridge{ $bridge_mappings:
         before => Service['neutron-ovs-agent-service'],

tox.ini

@@ -6,8 +6,8 @@ ignore_basepython_conflict = True
 
 [testenv]
 basepython = python3
-install_command = pip install -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} {opts} {packages}
 
 [testenv:releasenotes]
-deps = -r{toxinidir}/doc/requirements.txt
+deps = -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+       -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html