Use tox_install convention

Copied from networking-midonet.

Closes-Bug: #1646436
Change-Id: Ic66367eb797bddd3b7e0ffd2a65c0a3f719507f1

requirements.txt

@@ -4,4 +4,3 @@
 
 pbr>=1.6 # Apache-2.0
 Babel>=2.3.4 # BSD
--e git://git.openstack.org/openstack/neutron.git@master#egg=neutron

tools/tox_install.sh

@@ -0,0 +1,16 @@
+#! /bin/sh
+
+set -e
+
+DIR=$(dirname $0)
+${DIR}/tox_install_project.sh neutron neutron $*
+
+CONSTRAINTS_FILE=$1
+shift
+
+install_cmd="pip install"
+if [ $CONSTRAINTS_FILE != "unconstrained" ]; then
+    install_cmd="$install_cmd -c$CONSTRAINTS_FILE"
+fi
+
+$install_cmd -U $*

tools/tox_install_project.sh

@@ -0,0 +1,52 @@
+#!/bin/sh
+
+# Many of neutron's repos suffer from the problem of depending on neutron,
+# but it not existing on pypi.
+
+# This wrapper for tox's package installer will use the existing package
+# if it exists, else use zuul-cloner if that program exists, else grab it
+# from neutron master via a hard-coded URL. That last case should only
+# happen with devs running unit tests locally.
+
+# From the tox.ini config page:
+# install_command=ARGV
+# default:
+# pip install {opts} {packages}
+
+PROJ=$1
+MOD=$2
+shift 2
+
+ZUUL_CLONER=/usr/zuul-env/bin/zuul-cloner
+neutron_installed=$(echo "import ${MOD}" | python 2>/dev/null ; echo $?)
+BRANCH_NAME=master
+
+set -e
+
+CONSTRAINTS_FILE=$1
+shift
+
+install_cmd="pip install"
+if [ $CONSTRAINTS_FILE != "unconstrained" ]; then
+    install_cmd="$install_cmd -c$CONSTRAINTS_FILE"
+fi
+
+if [ $neutron_installed -eq 0 ]; then
+    echo "ALREADY INSTALLED" > /tmp/tox_install-${PROJ}.txt
+    echo "${PROJ} already installed; using existing package"
+elif [ -x "$ZUUL_CLONER" ]; then
+    echo "ZUUL CLONER" > /tmp/tox_install-${PROJ}.txt
+    cwd=$(/bin/pwd)
+    cd /tmp
+    $ZUUL_CLONER --cache-dir \
+        /opt/git \
+        --branch ${BRANCH_NAME} \
+        git://git.openstack.org \
+        openstack/${PROJ}
+    cd openstack/${PROJ}
+    $install_cmd -e .
+    cd "$cwd"
+else
+    echo "PIP HARDCODE" > /tmp/tox_install-${PROJ}.txt
+    $install_cmd -U -egit+https://git.openstack.org/openstack/${PROJ}@${BRANCH_NAME}#egg=${PROJ}
+fi

tox.ini

@@ -7,7 +7,7 @@ skipsdist = True
 setenv = VIRTUAL_ENV={envdir}
          PYTHONWARNINGS=default::DeprecationWarning
 usedevelop = True
-install_command = pip install -U {opts} {packages}
+install_command = {toxinidir}/tools/tox_install.sh {env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands = find . -type f -name "*.py[c|o]" -delete