map destructuring: prevent evaluation of values in :or when they are not used/needed

Description

The name :or implies this should behave as "or" and be "lazy" but it's not the case currently.
The following gist shows the issue. :x is present in the map but we eval the default value:

Environment

None

Status

Assignee

Unassigned

Reporter

Max Penet

Labels

Approval

Triaged

Patch

None

Affects versions

Priority

Trivial
Configure