Add to existing channels if CONDA_CHANNELS is preset

gitlab/functions.sh

@@ -355,7 +355,11 @@ install_miniconda() {
 # $2: typically, the value of ${CI_COMMIT_TAG} or empty
 # given the current visibility/tagging conditions of the package.
 set_conda_channels() {
-  CONDA_CHANNELS=() #resets bash array
+  if [ -z "${CONDA_CHANNELS+abc}" ]; then
+    CONDA_CHANNELS=() #sets bash array
+  else
+    log_info "Appending to existing \$\{CONDA_CHANNELS\} setup..."
+  fi
   if [ "${1}" == "public" ]; then
     if [ -z "${2}" ]; then #public beta build
       CONDA_CHANNELS+=('public/conda/label/beta')