[FIX] runbot_merge: freeze being triggered upon reopening the wizard

The freeze wizard was implemented using a single action to open and
validate the dialog.

This was a mistake, as it means if there are no errors left (e.g. all
the PRs being waited for are now validated) trying to view the freeze
wizard will immediately validate it and commit the freeze, which is
unexpected, surprising, and unsafe e.g.

- open wizard
- add freeze prs
- add a required pr or two
- close and go do something else
- be told that more PRs need to be waited for
- reopen wizard
- oops freeze is done

So split the "open action" part of `action_freeze` into opening the
action and performing the freeze. The "freeze" / "view freeze" button
on the project only activates the latter, and the actual freeze
operation is only triggered from the wizard's "Freeze" button.

Part of #559.

runbot_merge/models/project.py

@@ -117,4 +117,4 @@ class Project(models.Model):
             'branch_name': self._next_freeze(),
             'release_pr_ids': [(0, 0, {'repository_id': repo.id}) for repo in self.repo_ids]
         })
-        return w.action_freeze()
+        return w.action_open()

runbot_merge/models/project_freeze/__init__.py

@@ -56,21 +56,24 @@ class FreezeWizard(models.Model):
 
         return {'type': 'ir.actions.act_window_close'}
 
+    def action_open(self):
+        return {
+            'type': 'ir.actions.act_window',
+            'target': 'new',
+            'name': f'Freeze project {self.project_id.name}',
+            'view_mode': 'form',
+            'res_model': self._name,
+            'res_id': self.id,
+        }
+
     def action_freeze(self):
         """ Attempts to perform the freeze.
         """
-        project_id = self.project_id
         # if there are still errors, reopen the wizard
         if self.errors:
-            return {
-                'type': 'ir.actions.act_window',
-                'target': 'new',
-                'name': f'Freeze project {project_id.name}',
-                'view_mode': 'form',
-                'res_model': self._name,
-                'res_id': self.id,
-            }
+            return self.action_open()
 
+        project_id = self.project_id
         # need to create the new branch, but at the same time resequence
         # everything so the new branch is the second one, just after the branch
         # it "forks"

runbot_merge/tests/test_multirepo.py

@@ -1152,6 +1152,7 @@ def test_freeze_complete(env, project, repo_a, repo_b, repo_c, users, config):
     w = project.action_prepare_freeze()
     w2 = project.action_prepare_freeze()
     assert w == w2, "each project should only have one freeze wizard active at a time"
+    assert w['res_model'] == 'runbot_merge.project.freeze'
 
     w_id = env[w['res_model']].browse([w['res_id']])
     assert w_id.branch_name == '1.1', "check that the forking incremented the minor by 1"
@@ -1188,6 +1189,14 @@ def test_freeze_complete(env, project, repo_a, repo_b, repo_c, users, config):
 
     assert not w_id.errors
 
+    # assume the wizard is closed, re-open it
+    w = project.action_prepare_freeze()
+    assert w['res_model'] == 'runbot_merge.project.freeze'
+    assert w['res_id'] == w_id.id, "check that we're still getting the old wizard"
+    w_id = env[w['res_model']].browse([w['res_id']])
+    assert w_id.exists()
+
+    # actually perform the freeze
     r = w_id.action_freeze()
     # check that the wizard was deleted
     assert not w_id.exists()