Fix kolla-ansible to work with pyenv-virtualenv

One of the pyenv-virtualenv-set-up aliases depends on a symlink.
It seems pyenv runs the bash script from such a path and it fails
because of a failing comparison (VIRTUAL_ENV not detected).

The VIRTUAL_ENV is ensured to be fully resolved as well for safety.

This requires readlink from GNU coreutils but all supported platforms
have it by default.

Extra comments included, as well as simplification of directory
detection - readlink handles this (not that `bin` itself was
ever a symlink...).

Closes-Bug: #1903887
Co-Authored-By: Radosław Piliszek <[email protected]>
Change-Id: I2fe6eb13ce7be68d346b1b3b7036859f34c896c4
(cherry picked from commit aaab1d1)

Author: zengchen228

tools/kolla-ansible

@@ -66,20 +66,24 @@ function check_environment_coherence {
 
 function find_base_dir {
     local dir_name
-    dir_name=$(cd "$(dirname "$0")" &>/dev/null && pwd)
+    dir_name=$(dirname "$0")
+    # NOTE(yoctozepto): Fix the case where dir_name is a symlink and VIRTUAL_ENV might not be. This
+    # happens with pyenv-virtualenv, see https://bugs.launchpad.net/kolla-ansible/+bug/1903887
+    dir_name=$(readlink -e "$dir_name")
     if [ -z "$SNAP" ]; then
         if [[ ${dir_name} == "/usr/bin" ]]; then
             BASEDIR=/usr/share/kolla-ansible
         elif [[ ${dir_name} == "/usr/local/bin" ]]; then
             BASEDIR=/usr/local/share/kolla-ansible
-        elif [[ -n ${VIRTUAL_ENV} ]] && [[ ${dir_name} == "${VIRTUAL_ENV}/bin" ]]; then
+        elif [[ -n ${VIRTUAL_ENV} ]] && [[ ${dir_name} == "$(readlink -e "${VIRTUAL_ENV}/bin")" ]]; then
             if test -f ${VIRTUAL_ENV}/lib/python*/site-packages/kolla-ansible.egg-link; then
                 # Editable install.
                 BASEDIR="$(head -n1 ${VIRTUAL_ENV}/lib/python*/site-packages/kolla-ansible.egg-link)"
             else
                 BASEDIR="${VIRTUAL_ENV}/share/kolla-ansible"
             fi
         else
+            # Running from sources (repo).
             BASEDIR="$(dirname ${dir_name})"
         fi
     else