Fix variable name in environment variable updates (eth-cscs#291)

Fixes eth-cscs#290

Author: lmeinen

stackinator/etc/envvars.py

@@ -598,7 +598,7 @@ def meta_impl(args):
         for var_name, value in recipe_vars["scalar"].items():
             spack_vars["values"]["scalar"][var_name] = value
         for var_name, updates in recipe_vars["list"].items():
-            spack_vars["values"]["list"].setdefault(name, [])
+            spack_vars["values"]["list"].setdefault(var_name, [])
             spack_vars["values"]["list"][var_name] += updates
 
         # update the global meta data to include the environment variable state