unable to update assignees when 'update_existing: true'

[LongOddCode]

Hi,

When I set update_existing: true, everything is changed except the assignees.

[dblock]

This looks by design. I'll be happy to add support for things like update_existing: assignees, labels, body on top of #112 once that's merged.

[JasonEtco]

Hey 👋 this isn't intentional, but it is expected - I'd be open to a PR adding support for updating more than just the body if update_existing is true and an existing match is found 👍