[html-formfu] Problem with constraint When

[Cosmin Budrica]

I can't trigger then constraint when it's supposed to, it always stays
on the Required constraint.

Here's the code:
---
elements:
 - type: Select
   name: school_fk
   label: University
 - type: Text
   name: school
   constraints:
     - type: Required
       when:
         - field: school_fk
         - value: x

the school_fk select is populated with a structure like:
[ ['x', 'Other schools'], [1, 'University 1'], [...] ]

What am I doing wrong?