Since [1], the `insert` method accepts the `html` option to
automatically cast record fields marked as `html` to markup. Before
this PR, this option was ignored after the first insertion if the
field value remained the same.
Steps to reproduce this issue:
- Insert a message without passing the `html` option: the body field is
an instance of string.
- Insert the same message setting the `html` option to true: the body
field of the message is still an instance of string while it should be
an instance of markup.
This PR fixes this issue.
[1]: https://github.com/odoo/odoo/pull/139501closesodoo/odoo#149953
Signed-off-by: Matthieu Stockbauer (tsm) <tsm@odoo.com>