Restrict to loopy lang version 2017.2.1 for now

python/dune/perftool/pdelab/localoperator.py

@@ -514,6 +514,7 @@ def extract_kernel_from_cache(tag, name, signature, wrap_in_cgen=True, add_timin
     from loopy import Options
     opt = Options(ignore_boostable_into=True,
                   check_dep_resolution=False,
+                  enforce_variable_access_ordered="no_check",
                   )
 
     # Create the kernel
@@ -526,7 +527,7 @@ def extract_kernel_from_cache(tag, name, signature, wrap_in_cgen=True, add_timin
                          options=opt,
                          silenced_warnings=silenced,
                          name=name,
-                         lang_version=(2018, 1),
+                         lang_version=(2017, 2, 1),
                          )
 
     from loopy import make_reduction_inames_unique