The call to assert() is not appropriate, better use a SAL_WARN_IF
instead.

The call to DAVProperties::createUCBPropName() method immediately
after will take care of the missing namespace.

The change to assert() was introduced in commit
dd9c15b3

In libreoffice-5-1 branch it was introduced in commit
0ee79446

Change-Id: Ib9b85426fc84907fb12f70759a189cedcf117b3a
Reviewed-on: https://gerrit.libreoffice.org/20380Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
(cherry picked from commit 9b9329e4)
Reviewed-on: https://gerrit.libreoffice.org/20711Reviewed-by: Giuseppe Castagno <giuseppe.castagno@acca-esse.eu>
Reviewed-by: Christian Lohmaier <lohmaier+LibreOffice@googlemail.com>
Tested-by: Christian Lohmaier <lohmaier+LibreOffice@googlemail.com>