Field_geom::reset() failed to reset its base Field_blob. 
The range optimizer used the un-initilized field during optimization and execution.

mysql-test/r/gis.result:
  New test case.
mysql-test/t/gis.test:
  New test case.
sql/field.h:
  Field_geom::reset() must call Field_blob::reset(), even if the field is not nullable.