Why 'where(block: true)' doesn't work with 'set block'?

[Andrew]

It works for me using v0.11.1:

#show quote.where(block: true): set block(spacing: 5em)
// #show quote.where(block: true): block.with(spacing: 5em)
// #show quote.where(block: true): set block(above: 5em, below: 5em)

#lorem(25)

#quote[
  inline quote
]

#lorem(25)

#quote(block: true)[
  block quote
]

#lorem(25)

But there is a small caveat: To make a block quote with a border on the left side, like on GitHub - #4 by SillyFreak.