The cause of this was several different bugs:
- When using binary logging with binlog_row_image=FULL
the all bits in read_set was set, which caused a
different (wrong) pattern for marking vcol_set.
- TABLE::mark_virtual_columns_for_write() didn't in all
cases mark vcol_set with the vcol_field.
- TABLE::update_virtual_fields() has to update all
vcol fields on REPLACE if binary logging with FULL
is used.
- VCOL_UPDATE_INDEXED should update all vcol fields part
of an index that was not updated by VCOL_UPDATE_FOR_READ
- max_row_length() calculated length of NULL and not
used fields. This didn't cause any crash, but used
more memory than needed.
