Moved chdir in _run_model, and made sure before raising error chdir back

Otherwise could happen that raise came before chdir back to initial_cwd,
and unittest discovery which runs everything in one process had breaking
tests following the missed chdir back to initial_cwd

mopyregtest/modelicaregressiontest.py

@@ -222,13 +222,9 @@ def _import_and_simulate(self):
             pathlib.Path.mkdir(self.result_folder_path)
             self.result_folder_created = True
 
-        os.chdir(self.result_folder_path)
-
         # Run the scripts for import and simulation
         self._run_model()
 
-        os.chdir(self.initial_cwd)
-
         return
 
     @staticmethod
@@ -457,6 +453,8 @@ def _run_model(self):
         out : None
 
         """
+        os.chdir(self.result_folder_path)
+
         for tool in self.tools:
             tool_executable = tool
 
@@ -528,14 +526,21 @@ def _run_model(self):
 
                 # Check output: Both simulation binary and simulation result must exist now
                 if not sim_binary_path.exists():
+                    os.chdir(self.initial_cwd)
+
                     raise AssertionError(
                         f"The expected simulation binary at {sim_result_path} does not exist. "
                         + f"Please check the output from the simulation tool:\n\n{omc_messages}")
 
                 if not sim_result_path.exists():
+                    os.chdir(self.initial_cwd)
+
                     raise AssertionError(
                         f"The expected simulation result at {sim_result_path} does not exist. "
                         + f"Please check the output from the simulation tool:\n\n{omc_messages}")
+
+        os.chdir(self.initial_cwd)
+
         return
 
     @staticmethod