Merge branch 'PMPY-1707' into 'integration'

PMPY-1707 ZeroDivisionError when calculating alignments for an empty trace with a model that allows a complete firing sequence with only tau model moves

Closes PMPY-1707

See merge request process-mining/pm4py/pm4py-core!662

pm4py/algo/conformance/alignments/petri_net/algorithm.py

@@ -114,8 +114,9 @@ def apply_trace(trace, petri_net, initial_marking, final_marking, parameters=Non
 
     ltrace_bwc = trace_cost_function_sum + best_worst_cost
 
-    fitness = 1 - (ali['cost'] // align_utils.STD_MODEL_LOG_MOVE_COST) / (
-                ltrace_bwc // align_utils.STD_MODEL_LOG_MOVE_COST) if ltrace_bwc > 0 else 0
+    fitness_num = ali['cost'] // align_utils.STD_MODEL_LOG_MOVE_COST
+    fitness_den = ltrace_bwc // align_utils.STD_MODEL_LOG_MOVE_COST
+    fitness = 1 - fitness_num / fitness_den if fitness_den > 0 else 0
 
     # other possibility: avoid integer division but proceed to rounding.
     # could lead to small differences with respect to the adopted-since-now fitness