Update TOX_CONSTRAINTS_FILE for stable/zed

Update the URL to the upper-constraints file to point to the redirect
rule on releases.openstack.org so that anyone working on this branch
will switch to the correct upper-constraints list automatically when
the requirements repository branches.

Until the requirements repository has as stable/zed branch, tests will
continue to use the upper-constraints list on master.

Change-Id: Ie7f17b44f0dd48a4d20f6d28c8dfa1e12f839d58

.gitreview

@@ -2,3 +2,4 @@
 host=review.opendev.org
 port=29418
 project=openstack/watcher.git
+defaultbranch=stable/zed

.zuul.yaml

@@ -1,4 +1,5 @@
 - project:
+    queue: watcher
     templates:
       - check-requirements
       - openstack-cover-jobs
@@ -14,7 +15,6 @@
         - watcherclient-tempest-functional
         - watcher-tempest-functional-ipv6-only
     gate:
-      queue: watcher
       jobs:
         - watcher-tempest-functional
         - watcher-tempest-functional-ipv6-only

tox.ini

@@ -9,7 +9,7 @@ basepython = python3
 usedevelop = True
 allowlist_externals = find
                       rm
-install_command = pip install -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} {opts} {packages}
+install_command = pip install -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/zed} {opts} {packages}
 setenv =
    VIRTUAL_ENV={envdir}
 deps =

watcher/db/sqlalchemy/api.py

@@ -44,7 +44,11 @@ _FACADE = None
 def _create_facade_lazily():
     global _FACADE
     if _FACADE is None:
-        _FACADE = db_session.EngineFacade.from_config(CONF)
+        # FIXME(amoralej): Remove autocommit=True (and ideally use of
+        # LegacyEngineFacade) asap since it's not compatible with SQLAlchemy
+        # 2.0.
+        _FACADE = db_session.EngineFacade.from_config(CONF,
+                                                      autocommit=True)
     return _FACADE