[IMP] runbot_merge: split tagging cron out of main progress cron

They're completely independent (or should be), and there's no reason
for the tagging cron to extend the "lifetime" of the main cron's
transaction (and thus extend the odds of racey behaviour).

runbot_merge/data/merge_cron.xml

@@ -9,7 +9,17 @@
     <field name="numbercall">-1</field>
     <field name="doall" eval="False"/>
   </record>
-    <record model="ir.cron" id="fetch_prs_cron">
+  <record model="ir.cron" id="feedback_cron">
+    <field name="name">Send feedback to PR</field>
+    <field name="model_id" ref="model_runbot_merge_project"/>
+    <field name="state">code</field>
+    <field name="code">model._send_feedback()</field>
+    <field name="interval_number">1</field>
+    <field name="interval_type">minutes</field>
+    <field name="numbercall">-1</field>
+    <field name="doall" eval="False"/>
+  </record>
+  <record model="ir.cron" id="fetch_prs_cron">
     <field name="name">Check for PRs to fetch</field>
     <field name="model_id" ref="model_runbot_merge_project"/>
     <field name="state">code</field>

runbot_merge/models/pull_requests.py

@@ -242,7 +242,12 @@ class Project(models.Model):
                         })
 
                     logger.info("Created staging %s (%s)", st, staged)
+        # I have no idea why this is necessary for tests to pass, the only
+        # DB update done not through the ORM is when receiving a notification
+        # that a PR has been closed
+        self.invalidate_cache()
 
+    def _send_feedback(self):
         Repos = self.env['runbot_merge.repository']
         ghs = {}
         # noinspection SqlResolve

runbot_merge/tests/test_basic.py

@@ -31,6 +31,7 @@ def test_trivial_flow(env, repo):
     ])
     assert pr.state == 'opened'
     env['runbot_merge.project']._check_progress()
+    env['runbot_merge.project']._send_feedback()
     assert pr1.labels == {'seen 🙂'}
     # nothing happened
 
@@ -42,6 +43,7 @@ def test_trivial_flow(env, repo):
     repo.post_status(c1, 'success', 'ci/runbot')
     assert pr.state == 'validated'
     env['runbot_merge.project']._check_progress()
+    env['runbot_merge.project']._send_feedback()
     assert pr1.labels == {'seen 🙂', 'CI 🤖'}
 
     pr1.post_comment('hansen r+', 'reviewer')
@@ -50,6 +52,7 @@ def test_trivial_flow(env, repo):
     # can't check labels here as running the cron will stage it
 
     env['runbot_merge.project']._check_progress()
+    env['runbot_merge.project']._send_feedback()
     assert pr.staging_id
     assert pr1.labels == {'seen 🙂', 'CI 🤖', 'r+ 👌', 'merging 👷'}
 
@@ -60,6 +63,7 @@ def test_trivial_flow(env, repo):
     assert re.match('^force rebuild', staging_head.message)
 
     env['runbot_merge.project']._check_progress()
+    env['runbot_merge.project']._send_feedback()
     assert pr.state == 'merged'
     assert pr1.labels == {'seen 🙂', 'CI 🤖', 'r+ 👌', 'merged 🎉'}
 
@@ -235,6 +239,7 @@ def test_staging_conflict(env, repo):
     repo.post_status(c3, 'success', 'ci/runbot')
     pr2.post_comment('hansen r+', "reviewer")
     env['runbot_merge.project']._check_progress()
+    env['runbot_merge.project']._send_feedback()
     p_2 = env['runbot_merge.pull_requests'].search([
         ('repository.name', '=', repo.name),
         ('number', '=', pr2.number)
@@ -306,6 +311,7 @@ def test_staging_merge_fail(env, repo, users):
     prx.post_comment('hansen r+', "reviewer")
 
     env['runbot_merge.project']._check_progress()
+    env['runbot_merge.project']._send_feedback()
     pr1 = env['runbot_merge.pull_requests'].search([
         ('repository.name', '=', repo.name),
         ('number', '=', prx.number)
@@ -502,6 +508,7 @@ def test_edit(env, repo):
     prx.base = '2.0'
     assert not pr.exists()
     env['runbot_merge.project']._check_progress()
+    env['runbot_merge.project']._send_feedback()
     assert prx.labels == set()
 
     prx.base = '1.0'