2.6.1: could `stg series` default to indexes output?

[lkraav]

Often using patch indexes is faster and simpler than tab-completing, esp. if a stack contains many chore- etc similar-starting patches.

Turns out stg.alias doesn't allow masking built-in commands, so below failed

[stgit "alias"]
  series = series -I

Am I missing any config options?