explainb.js failed on OS X 10.8 C++11 DEBUG

MongoDB shell version: 2.5.3-pre-

connecting to: 127.0.0.1:27999/test

false

assert: ["BtreeCursor a_1_b_1"] != ["BtreeCursor b_1_a_1"] are not equal : undefined

Error: Printing Stack Trace

    at printStackTrace (src/mongo/shell/utils.js:38:15)

    at doassert (src/mongo/shell/assert.js:6:5)

    at Function.assert.eq (src/mongo/shell/assert.js:32:5)

    at /data/mci/git@github.commongodb/mongo.git/master/jstests/explainb.js:16:8

2013-10-16T18:53:11.374-0400 ["BtreeCursor a_1_b_1"] != ["BtreeCursor b_1_a_1"] are not equal : undefined at src/mongo/shell/assert.js:7

failed to load: /data/mci/git@github.commongodb/mongo.git/master/jstests/explainb.js