Blocked revisions 76967-76968 via svnmerge

........
  r76967 | mark.dickinson | 2009-12-21 11:31:54 +0000 (Mon, 21 Dec 2009) | 1 line

  Fix reference counts for test_long_and_overflow.
........
  r76968 | mark.dickinson | 2009-12-21 12:15:48 +0000 (Mon, 21 Dec 2009) | 1 line

  Additional edge-case tests for test_long_and_overflow.
........