histedit: avoid using a list comprehension to fill a list with fixed values

Flagged by PyCharm as an unused assignment for the variable in the list.

Differential Revision: https://phab.mercurial-scm.org/D7762

hgext/histedit.py

@@ -308,7 +308,7 b' Commands:'
         if len(a.verbs):
             v = b', '.join(sorted(a.verbs, key=lambda v: len(v)))
         actions.append(b" %s = %s" % (v, lines[0]))
-        actions.extend([b'  %s' for l in lines[1:]])
+        actions.extend([b'  %s'] * (len(lines) - 1))
 
     for v in (
         sorted(primaryactions)