When edges of a polygon coicide, it can form an pike, that is turned into a line after an operation.
        In this case a former polygon point can be an end of a single line, and that case wasn't properly handled.


per-file comments:
  mysql-test/r/gis-precise.result
bug 839327 Crash in Gcalc_operation_reducer::end_couple with ST_UNION and MULTIPOLYGONs in 5.3-gis.
        test result updated.

  mysql-test/t/gis-precise.test
bug 839327 Crash in Gcalc_operation_reducer::end_couple with ST_UNION and MULTIPOLYGONs in 5.3-gis.
        test case added.

  sql/gcalc_tools.cc
bug 839327 Crash in Gcalc_operation_reducer::end_couple with ST_UNION and MULTIPOLYGONs in 5.3-gis.
        in the scev_two_ends case check if we have single line ending on a polygon node.