fdo#72148 if expecting table at begin, explicitly set it so

Change-Id: Ic876603e5860b987280b73726fd79a071a9c833c
flat text DB: fix move by bookmark

To test whether the range [a,b( is *before* e,
compare e to b, not to a.

This makes a difference when a==b, which happens for row 0 (header)
when there is no header.

Change-Id: I629b71936f82a468febe0360909264dd80304437