This partially reverts #1257 / #1272 / 553531711b where the 404 was introduced.
A 406 error is still returned when requesting a single object via accept header.
Returning an error when no rows are changed can be introduced through a different syntax again, see the discussion in #2164.
Fixes#2343
Signed-off-by: Wolfgang Walther <walther@technowledgy.de>