[FIX] util/orm: verify constraint rollback

If there constraint wasn't there attempting to add it may cause errors.
Since the rollback should only revert what's done in this util we should
record if the constraint was there in the first place.

closes #185

Signed-off-by: Christophe Simonis (chs) <chs@odoo.com>

src/util/orm.py

@@ -567,11 +567,13 @@ def custom_module_field_as_manual(env, rollback=True, do_flush=False):
     updated_field_ids = []
 
     # 2.1 Convert fields not in the registry of models already in the registry.
+    # defuse constraint for manual fields, ref: odoo/odoo@3d2f766
+    env.cr.execute("SELECT 1 FROM pg_constraint WHERE conname = 'ir_model_fields_name_manual_field'")
+    have_constraint = bool(env.cr.rowcount)
+    if have_constraint:
+        env.cr.execute("ALTER TABLE ir_model_fields DROP CONSTRAINT ir_model_fields_name_manual_field")
     # In the past, some models added the reserved word `env` as field (e.g. `payment.acquirer`)
     # if the field was not correctly removed from the database during past upgrades, the field remains in the database.
-    if version_gte("saas~16.4"):
-        # defuse constraint for manual fields, ref: odoo/odoo@3d2f766
-        env.cr.execute("ALTER TABLE ir_model_fields DROP CONSTRAINT IF EXISTS ir_model_fields_name_manual_field")
     reserved_words = ["env"]
     ignores = {"ir.actions.server": ["condition"], "ir.ui.view": ["page"]}
     for model in models:
@@ -731,7 +733,7 @@ def _add_magic_fields(self):
 
         if updated_field_ids:
             env.cr.execute("UPDATE ir_model_fields SET state = 'base' WHERE id IN %s", (tuple(updated_field_ids),))
-        if version_gte("saas~16.4"):
+        if have_constraint:
             # restore constraint for manual fields, ref: odoo/odoo@3d2f766
             env.cr.execute(
                 r"""