Conditional deactivate env, then activate new env

This is to address a bug where a currently active env would cause the
hpc init script to load the flepimop env not cleanly. Determine the
currently active env if there is one and if it is not the flepimop env
deactivate it with message to the user.

batch/hpc_init.sh

@@ -52,6 +52,11 @@ if [ -z "${FLEPI_CONDA}" ]; then
     fi
     echo "Using '$FLEPI_CONDA' for \$FLEPI_CONDA."
 fi
+CURRENT_CONDA_ENV=$( conda info | grep "active environment" | awk -F ':' '{print $2}' | xargs )
+if [ "$CURRENT_CONDA_ENV" != "None" ] && [ "$CURRENT_CONDA_ENV" != "$FLEPI_CONDA" ]; then
+    echo "Detected an active conda environment '$CURRENT_CONDA_ENV'. This will be deactivated and the '$FLEPI_CONDA' environment will be activated."
+    conda deactivate
+fi
 conda activate $FLEPI_CONDA
 
 # Check the conda environment is valid