Issue #177: Duplicate entry error in cache_invalidation table (conservancy/kallithea)

[Dominik Ruf]

New issue 177: Duplicate entry error in cache_invalidation table
https://bitbucket.org/conservancy/kallithea/issues/177/duplicate-entry-error-in

Dominik Ruf:

>From time to time I get the following error.

WebApp Error: <class 'sqlalchemy.exc.IntegrityError'>: (IntegrityError) (1062, "Duplicate entry 'myrepo' for key 'cache_key'") 'INSERT INTO cache_invalidation (cache_key, cache_args, cache_active) VALUES (%s, %s, %s)' ('myrepo', 'myrepo', 1)


```
#!text
...
Module kallithea.model.db:1449 in scm_instance_cached
>>  valid = CacheInvalidation.test_and_set_valid(rn, None, valid_cache_keys=valid_cache_keys)
Module kallithea.model.db:2141 in test_and_set_valid
>>  Session().commit()
Module sqlalchemy.orm.session:710 in commit
...
```

When I look at the code it seems that in case an inactive inv_obj is found it is set to active and re-add. But re-adding an object fails.

https://bitbucket.org/conservancy/kallithea/src/8bc8366a6874640c73c20ce8ecfb596c0b4134db/kallithea/model/db.py?at=default&fileviewer=file-view-default#db.py-2134