Improve fossildb conflict error message  (#4288)
Improve fossildb conflict error message  (#4288)

* rephrase error message
* Merge branch 'master' into improve-fossil-error-message
* Merge branch 'master' into improve-fossil-error-message

scalableminds/webknossos,scalableminds/webknossos,scalableminds/webknossos,scalableminds/webknossos,scalableminds/webknossos,scalableminds/webknossos