cd'ing to a directory with blank raises error

```
Initializing the Shuffled Complex Evolution (SCE-UA) algorithm with 50000 repetitions
The objective function will be minimized
Starting burn-in sampling...
root : INFO serial model execution started
root : INFO start execution of simulation setup: tga_analysis_01
Traceback (most recent call last):
File "propti/propti_run.py", line 64, in
res = pr.run_optimisation(ops, setups, optimiser)
File "/somedir/Untitled Folder 2/anotherdir/propti/propti/spotpy_wrapper.py", line 153, in run_optimisation
results=sampler.sample(opt.repetitions, ngs=ngs, max_loop_inc=opt.max_loop_inc)
File "/somedir/.local/lib/python3.6/site-packages/spotpy/algorithms/sceua.py", line 189, in sample
for rep, randompar, simulations in self.repeat(param_generator):
File "/somedir/.local/lib/python3.6/site-packages/spotpy/parallel/sequential.py", line 27, in __call__
data = self.process(job)
File "/somedir/.local/lib/python3.6/site-packages/spotpy/algorithms/sceua.py", line 75, in simulate
return _algorithm.simulate(self, id_params_tuple)
File "/somedir/.local/lib/python3.6/site-packages/spotpy/algorithms/_algorithm.py", line 467, in simulate
model_result = self.setup.simulation(self.partype(*all_params))
File "/somedir/Untitled Folder 2/anotherdir/propti/propti/spotpy_wrapper.py", line 81, in simulation
run_simulations(self.setups, self.optimiser.num_subprocesses)
File "/somedir/Untitled Folder 2/anotherdir/propti/propti/basic_functions.py", line 148, in run_simulations
run_simulation_serial(s, best_para_run)
File "/somedir/Untitled Folder 2/anotherdir/propti/propti/basic_functions.py", line 173, in run_simulation_serial
stdout=log_file, stderr=log_file)
File "/usr/lib/python3.6/subprocess.py", line 311, in check_call
raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command 'cd /somedir/Untitled Folder 2/anotherdir/tga_analysis_run_01/rundir_srbp2j50 && fds model_input.file' returned non-zero exit status 2.
```
Happened during automated execution of the model.