assert: ["b562f33e55fac5be5e491ef29dde6f6b"] != [""] are not equal : A3
Error: Printing Stack Trace
at shell/utils.js:35:7
at shell/utils.js:46:1
at Function.eq (shell/utils.js:72:1)
at jstests/dbhash.js:35:8
at _funcs1:7:40
at Function.timeFunc (shell/utils.js:283:9)
at _funcs1:7:17
at Array.forEach (native)
at Number.<anonymous> (_funcs1:4:6)
at _funcs1:122:65
Sat Jul 23 20:10:48 exec error: shell/utils.js:47 ["b562f33e55fac5be5e491ef29dde6f6b"] != [""] are not equal : A3
throw msg;

assert: [""] != ["44630b03208785a5d03c20cc3d56c2de"] are not equal : A3
Error: Printing Stack Trace
at shell/utils.js:19:7
at shell/utils.js:30:1
at Function.eq (shell/utils.js:56:1)
at jstests/dbhash.js:35:8
at _funcs1:7:40
at Function.timeFunc (shell/utils.js:267:9)
at _funcs1:7:17
at Array.forEach (native)
at Number.<anonymous> (_funcs1:4:6)
at _funcs1:122:65
Mon Jun 6 19:20:20 exec error: shell/utils.js:31 [""] != ["44630b03208785a5d03c20cc3d56c2de"] are not equal : A3
throw msg;

One guess right now is that some collection in the test db is missing an id index while one dbhash command has a read mutex, causing dbhash to abort without generating output for all collections. In both failure cases I've seen this test runs at the same time as geo_center_spere2.js but that could be a red herring.