[server] Handle unique constraint violations under recent sqlite
The error message changed from "columns foo, bar, baz are not unique" to
"UNIQUE constraint failed: table.foo, table.bar, table.baz".
Closes #3564510
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/index.html
Files: /usr/share/doc/cubicweb-documentation/*.html