capped collection has different hash on master/slave at end of where4.js

http://buildbot.mongodb.org/builders/Linux%2064-bit%20DEBUG/builds/1193/steps/test_2/logs/stdio
http://buildlogs.mongodb.org/build/4fcae65bd2a60f6e9500021e/test/4fcb42e5d2a60f1206000598/

Both builds have been failing before this test for several days, so it's difficult to tell which commit is responsible.