nazca #134571 In align_iterative, the best distance is not correctly retrieved [done]

The current_dist is retrieved in the cache using "get()" with a default value of None.
The condition "if not current_dist" is thus checked if current_dist is None OR if the current_dist from the cache is the best possible one (i.e. O).

done in<not specified>
load left0.000
closed by#6ae9fff68d2f [align] Correctly check the best value, closes #134571