Move upper constraint logic to after python is installed

Currently if python is not already installed on the deployment host
the bootstrap-ansible script fails due to the way that the script
tries to check the python version installed (using python to do it).

This patch moves the logic until after python is actually installed
to cater for the situation where it may not already have been.

Change-Id: I06da3e84100b619e7c39962b7a43d4c8c7d707fa

scripts/bootstrap-ansible.sh

@@ -26,14 +26,10 @@ export ANSIBLE_PACKAGE=${ANSIBLE_PACKAGE:-"git+https://github.com/ansible/ansibl
 export ANSIBLE_ROLE_FILE=${ANSIBLE_ROLE_FILE:-"ansible-role-requirements.yml"}
 export SSH_DIR=${SSH_DIR:-"/root/.ssh"}
 export DEBIAN_FRONTEND=${DEBIAN_FRONTEND:-"noninteractive"}
-PYTHON_EXEC_PATH="$(which python2 || which python)"
-PYTHON_VERSION="$($PYTHON_EXEC_PATH -c 'import sys; print(".".join(map(str, sys.version_info[:3])))')"
-# Use https when Python with native SNI support is available
-UPPER_CONSTRAINTS_PROTO=$([ "$PYTHON_VERSION" == $(echo -e "$PYTHON_VERSION\n2.7.9" | sort -V | tail -1) ] && echo "https" || echo "http")
-# Set the location of the constraints to use for all pip installations
-export UPPER_CONSTRAINTS_FILE=${UPPER_CONSTRAINTS_FILE:-"$UPPER_CONSTRAINTS_PROTO://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt?id=$(awk '/requirements_git_install_branch:/ {print $2}' playbooks/defaults/repo_packages/openstack_services.yml)"}
+
 # Set the role fetch mode to any option [galaxy, git-clone]
 export ANSIBLE_ROLE_FETCH_MODE=${ANSIBLE_ROLE_FETCH_MODE:-galaxy}
+
 # virtualenv vars
 VIRTUALENV_OPTIONS="--always-copy"
 
@@ -98,6 +94,16 @@ elif [ -n "$HTTP_PROXY" ]; then
   PIP_OPTS="--proxy $HTTP_PROXY"
 fi
 
+# Figure out the version of python is being used
+PYTHON_EXEC_PATH="$(which python2 || which python)"
+PYTHON_VERSION="$($PYTHON_EXEC_PATH -c 'import sys; print(".".join(map(str, sys.version_info[:3])))')"
+
+# Use https when Python with native SNI support is available
+UPPER_CONSTRAINTS_PROTO=$([ "$PYTHON_VERSION" == $(echo -e "$PYTHON_VERSION\n2.7.9" | sort -V | tail -1) ] && echo "https" || echo "http")
+
+# Set the location of the constraints to use for all pip installations
+export UPPER_CONSTRAINTS_FILE=${UPPER_CONSTRAINTS_FILE:-"$UPPER_CONSTRAINTS_PROTO://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt?id=$(awk '/requirements_git_install_branch:/ {print $2}' playbooks/defaults/repo_packages/openstack_services.yml)"}
+
 # Create a Virtualenv for the Ansible runtime
 virtualenv --clear ${VIRTUALENV_OPTIONS} --system-site-packages --python="${PYTHON_EXEC_PATH}" /opt/ansible-runtime