merge: use the new action based mapping introduced in mergeresult obj Before this patch, we have good number of instances of following types: ``` for f, (m, args, msg) in mresult.actions: if m == ACTION_X: do_something ``` We iterate over the whole list and then filter for a certain action. Previous patch introduced a action based mapping in mergeresult object. The above code now looks like: ``` for f, args, msg in mresult.getactions([ACTION_X, ...]): do_something ``` Differential Revision: https://phab.mercurial-scm.org/D8831