409 conflict at deleting identities

. Oct 25 18:31:20 pixelated webapp[8370]: Started DELETE "/1/users/4bcc32767e0d77defa0862c6951ff694.json?identities=destroy" for 0.0.0.0 at 2016-10-25 18:31:20 +0200
. Oct 25 18:31:20 pixelated webapp[8370]: Processing by Api::UsersController#destroy as JSON
. Oct 25 18:31:20 pixelated webapp[8370]: Parameters: {"identities"=>"destroy", "version"=>"1", "id"=>"4bcc32767e0d77defa0862c6951ff694"}
. Oct 25 18:31:20 pixelated webapp[2498]: Started DELETE "/1/users/4bcc32767e0d77defa0862c6951ff694.json?identities=destroy" for 0.0.0.0 at 2016-10-25 18:31:20 +0200
. Oct 25 18:31:20 pixelated webapp[2498]: Processing by Api::UsersController#destroy as JSON
. Oct 25 18:31:20 pixelated webapp[2498]: Parameters: {"identities"=>"destroy", "version"=>"1", "id"=>"4bcc32767e0d77defa0862c6951ff694"}
. Oct 25 18:31:20 pixelated webapp[8370]: 409 Conflict
. Oct 25 18:31:20 pixelated webapp[8370]: /srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/couchrest-2.0.0/lib/couchrest/connection.rb:241:in `raise_response_error'
/srv/leap/webapp/vendor/
bundle/ruby/2.1.0/gems/couchrest-2.0.0/lib/couchrest/connection.rb:196:in `handle_response_code'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/couchrest-2.0.0/lib/couchrest/connection.rb
:185:in `send_and_parse_response'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/couchrest-2.0.0/lib/couchrest/connection.rb:170:in `execute'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/couchrest-2.0.0/lib/couchrest/connection.rb:73:in `put'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/couchrest-2.0.0/lib/couchrest/database.rb:155:in `save_doc'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/couchrest_model-0.0.0.0c1/lib/couchrest/model/persistence.rb:37:in `block (2 levels) in update'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/activesupport-0.0.0.0/lib/active_support/callbacks.rb:88:in `__run_callbacks__'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/activesupport-0.0.0.0/lib/active_support/callbacks.rb:778:in `_run_save_c
allbacks'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/activesupport-0.0.0.0/lib/active_support/callbacks.rb:81:in `run_callbacks'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/couchrest_model-0.0.0.0c1/lib/couchrest/model/persistence.rb:36:in `block in update'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/activesupport-0.0.0.0/lib/active_support/callbacks.rb:88:in `__run_callbacks__'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/activesupport-0.0.0.0/lib/active_support/callbacks.rb:778:in `_run_update_callbacks'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/activesupport-0.0.0.0/lib/active_support/callbacks.rb:81:in `run_callbacks'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/couchrest_model-0.0.0.0c1/lib/couchrest/model/persistence.rb:35:in `update'
/srv/leap/webapp/vendor/bundle/ruby/2.1.0/gems/couchrest_session_store-0.4.2/lib/couchrest/model/rotation.rb:18:in `update
C Oct 25 18:31:20 pixelated webapp[8370]: Completed 500 Internal Server Error in 78ms (Views: 0.3ms)

Hugh, it looks like there are two calls of:

Started DELETE "/1/users/4bcc32767e0d77defa0862c6951ff694.json?identities=destroy"

which might lead into this 409 conflict ?

(from redmine: created on 2016-10-26)