Problem:

The problem happens only when optimizer uses InnoDB for generating internal
temporary tables (aka intrinsic temporary tables).

A cached select cursor on intrinsic temporary table needs to be re-opened
whenever cursor is marked invalid.  When the cursor was restored using
the old record, we need to adjust the search mode (PAGE_CUR_GE needs to
be replaced with PAGE_CUR_G).  This is needed because we need to move past
the old record.

This mode adjustment was done only when prebuilt->m_temp_tree_modified flag
was set, which is incorrect.  This mode adjustment is needed not only when
prebuilt->m_temp_tree_modified flag is set, but also when the cached cursor is
marked invalid.

Solution:

Adjust the search mode unconditionally when restoring the cursor.

rb#20268 approved by Allen.