As in the inverse field that write the value into the <field>_env_default
we have to browse the record, the prefetch has the effect of calling
compute on the env-computed field which resets the value to it's
previous state before we have the occasion to store it.
When they don't have any key in the environment configuration files.
In the UI, when a field is set in a configuration file, the field is
readonly, if not the field is editable. Which means you can selectively
choose which fields depend on the environment and which can use a
"default" value stored in database.
Automatically add <field_name>_env_default for every field transformed
to a "computed from env" field, so a default value can be set. It will
be used when the configuration is not set in a configuration file
(when the key is absent, not empty).
Guewen Baconnier