histedit: minor refactoring of createmarkers check

We use a variable to store whether or not we can create obsolescence markers.
It makes the patch series more readable as we are going to reuse this
values in other places in the function.

hgext/histedit.py

@@ -750,6 +750,7 b' def _histedit(ui, repo, state, *freeargs'
 
     replacements = []
     state.keep = opts.get('keep', False)
+    supportsmarkers = obsolete.isenabled(repo, obsolete.createmarkersopt)
 
     # rebuild state
     if goal == 'continue':
@@ -881,7 +882,7 b' def _histedit(ui, repo, state, *freeargs'
         if mapping:
             movebookmarks(ui, repo, mapping, state.topmost, ntm)
             # TODO update mq state
-        if obsolete.isenabled(repo, obsolete.createmarkersopt):
+        if supportsmarkers:
             markers = []
             # sort by revision number because it sound "right"
             for prec in sorted(mapping, key=repo.changelog.rev):