histedit: do not use "min" on ctx

It does not crash but does not compare revision number at all. We actually
remove any call to min because the list is already topologically sorted.

hgext/histedit.py

@@ -594,7 +594,7 b' def between(repo, old, new, keep):'
     if ctxs and not keep:
         if repo.revs('(%ld::) - (%ld + hidden())', ctxs, ctxs):
             raise util.Abort(_('cannot edit history that would orphan nodes'))
-        root = min(ctxs)
+        root = ctxs[0] # list is already sorted by repo.set
         if not root.phase():
             raise util.Abort(_('cannot edit immutable changeset: %s') % root)
     return [c.node() for c in ctxs]