[pkg] prepare 3.17.15

[cache] fix a cache issue with an entity created without relation cache prefill Prefilling the relation cache has its benefits sometimes, but for massive imports it may be a memory hog. The caches should be kept coherent even if there was no prefill. Closes #3828155.

[web/test] add a test for some http response codes Related to #3648809

[views] remove reference to the MAPPING_CHECKERS dict (closes #3810219) Was removed by by the changeset 65d93a4fd11c ([multi-sources-removal] Drop pyrorql and zmqrql sources)

[web/ajax] Always return a json dict with a 'reason' key in case of ajax errors Sending sometimes a bare unicode string and sometimes a json-encoded dict seems like a bad idea.

[web/ajax] don't override any status code with 500 in ajax_error_handler If the request produced an error such as Unauthorized or NotFound, core_handle sets an appropriate status_out. Which is then overridden by the ajax error handler.

[web] Add asserts to the raw header conversion functions This API is terrible, but at least this might help us catch some errors in our conversion definitions.

[view] Delete dead(?) code from ReloadableMixIn Nothing seems to ever call user_callback on the Component, only on the request. Related to #3567793

Add a db-statement-timeout option for postgresql sources Use that new option to set the statement_timeout option when creating connections, except for maintenance operations (shell and upgrade). Closes #2547026

[test] use assertNotIsInstance instead of assert_(not isinstance(...))