load_m_file_data.m: prevent horse-race condition when saving and loading mat file

Should prevent spurious testsuite crashes as in https://git.dynare.org/Dynare/dynare/-/jobs/36592

src/read/load_m_file_data.m

@@ -46,6 +46,9 @@ if isoctave
 end
 
 save tmp__dataSet__.mat;
+% the following aims at preventing horse-race conditions between writing the
+% file and then immediately loading it, see https://git.dynare.org/Dynare/dseries/-/merge_requests/40
+rehash;
 
 [freq, init, data, varlist, tex, ops, tags] = load_mat_file_data('tmp__dataSet__.mat');