Ensure we install tempest-lib from git in tempest's tox venv

This commit adds installing tempest-lib from git to the tempest full
job's tox venv. Since by default tempest isn't being installed
globally anymore and when we do run tempest it is normally within a
tox venv that means previously the install from git flag isn't being
taken into account.

Change-Id: I98b0754c4a91690c9402fa2ae2c3e9ba9195d444
diff --git a/lib/tempest b/lib/tempest
index d3b40aa..6177ffe 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -517,14 +517,23 @@
     if use_library_from_git "tempest-lib"; then
         git_clone_by_name "tempest-lib"
         setup_dev_lib "tempest-lib"
+        # NOTE(mtreinish) For testing tempest-lib from git with tempest we need
+        # put the git version of tempest-lib in the tempest job's tox venv
+        export PIP_VIRTUAL_ENV=${PROJECT_VENV["tempest"]}
+        setup_dev_lib "tempest-lib"
+        unset PIP_VIRTUAL_ENV
     fi
 }
 
 # install_tempest() - Collect source and prepare
 function install_tempest {
-    install_tempest_lib
     git_clone $TEMPEST_REPO $TEMPEST_DIR $TEMPEST_BRANCH
     pip_install tox
+    pushd $TEMPEST_DIR
+    tox --notest -efull
+    PROJECT_VENV["tempest"]=${TEMPEST_DIR}/.tox/full
+    install_tempest_lib
+    popd
 }
 
 # init_tempest() - Initialize ec2 images