Add an explicit BRANCH_NAME to tox_install.sh

tools/tox_install.sh exists to deal with installing neutron without
neutron existing as a pypi package.

The way this operates causes problems in the periodic jobs on the stable
branches.  Make it explicit which branch to install in the gate
(zuul-cloner) and via pip (NEUTRON_PIP_LOCATION).

This is done with a BRANCH_NAME variable to make it trivial to change
once master is tagged as stable.

Change-Id: I0667580c3107d3c1e1888a1b2c2a222124d22fe3

tools/tox_install.sh

@@ -14,6 +14,7 @@
 # pip install {opts} {packages}
 
 ZUUL_CLONER=/usr/zuul-env/bin/zuul-cloner
+BRANCH_NAME=master
 neutron_installed=$(echo "import neutron" | python 2>/dev/null ; echo $?)
 
 set -e
@@ -35,6 +36,7 @@ elif [ -x "$ZUUL_CLONER" ]; then
     cd /tmp
     $ZUUL_CLONER --cache-dir \
         /opt/git \
+        --branch $BRANCH_NAME \
         git://git.openstack.org \
         openstack/neutron
     cd openstack/neutron
@@ -43,7 +45,7 @@ elif [ -x "$ZUUL_CLONER" ]; then
 else
     echo "PIP HARDCODE" > /tmp/tox_install.txt
     if [ -z "$NEUTRON_PIP_LOCATION" ]; then
-        NEUTRON_PIP_LOCATION="git+https://git.openstack.org/openstack/neutron#egg=neutron"
+        NEUTRON_PIP_LOCATION="git+https://git.openstack.org/openstack/neutron@$BRANCH_NAME#egg=neutron"
     fi
     $install_cmd -U -e ${NEUTRON_PIP_LOCATION}
 fi