Don't create a new venv if it already exists

templates/build_enstools.sh

@@ -33,15 +33,17 @@ if [ $(
   # Compile openmpi with schedulers=slurm
   spack install python@3.8:
 else
-  echo "py-enstools-compression already installed!"
+  echo "python@3.8: already installed!"
 fi
 
 # Link the python binary into the main folder so can be easily used later:
 
 spack load python@3.8:
 
-# Create virtual environment
-python3 -m venv --prompt AS venv
+if [ ! -d venv ]; then
+  # Create virtual environment
+  python3 -m venv --prompt AS venv
+fi
 
 # Load environment
 source venv/bin/activate