Broken get_paged_slice

get_paged_slice doesn't reset the start column filter for the second returned row sometimes. So instead of getting a slice:

row 0: <start_column>...<last_column_in_row>
row 1: <first column in a row>...<last_column_in_row>
row 2: <first column in a row>...

you sometimes get:

row 0: <start_column>...<last_column_in_row>
row 1: <start_column>...<last_column_in_row>
row 2: <first column in a row>...