Randolph, this test failure seem to first appear (on MCI) as of commit 84ff1694c. I tried to repro it but didn't succeed.

osx-108-dur-off aggregation_auth : mongos_slaveok.js

"assert failed"

• http://buildlogs.mongodb.org/mci_0.9_osx_108_dur_off/builds/675/test/aggregation_auth_0/mongos_slaveok.js
• http://mci.10gen.com/ui/task/mongodb_mongo_master_osx_108_dur_off_84ff1694c4bf92f3deef5c013ac9a5b912e6f96f_13_08_29_22_09_07_aggregation_auth_osx_108

linux-64 aggregation_auth : mongos_slaveok.js

"assert failed"

• http://buildlogs.mongodb.org/mci_0.9_linux_64/builds/685/test/aggregation_auth_0/mongos_slaveok.js
• http://mci.10gen.com/ui/task/mongodb_mongo_master_linux_64_84ff1694c4bf92f3deef5c013ac9a5b912e6f96f_13_08_29_22_09_07_aggregation_auth_linux_64