This works around an issue where unreplicated keys will not be matched everywhere.
This also avoids the cost of creating millions of bolt read transactions and allocating strings.
green:
TestFragment_RowsIteration/combinations
TestFragment_RoaringImportTopN
red: (needs Ben's attention)
PILOSA_TXSRC=rbf go test -v -run TestFragment_TopN_IDs -tags=' shardwidth20' "-gcflags=all=-d=checkptr=0"
also red: (one for Ben)
TestCursor_FirstNext_Quick/9 is throwing
panic: cannot find segment containing WAL page: 1
as we check the error back from checkpoint() in Rollback().
