We cannot cut a line from a polygon. So if the polygon fits the condition, and
        the intersection of a line and the polygon doesn't, we just skip the line.
        That rule wasn't applied if the line start was inside the polygon, which leaded
        to the assertion.

per-file comments:
  mysql-test/r/gis-precise.result
Fix for bug #801217 Assertion `t1->result_range' in Gcalc_operation_reducer::end_couple.
        test result updated.
  mysql-test/t/gis-precise.test
Fix for bug #801217 Assertion `t1->result_range' in Gcalc_operation_reducer::end_couple.
        test case added.
  sql/gcalc_tools.cc
Fix for bug #801217 Assertion `t1->result_range' in Gcalc_operation_reducer::end_couple.
        Don't mark the line as a border if it's inside a polygon that fits the result condition.