[REVERT] [VOTE] Release 0.12.0, release candidate #1

[zhaojing yu]

After careful consideration, we decided to restore the voting results due
to the serious issue found with bulkinsert/row-writing path (affecting
persisted data and resulting in duplicates). fix is here
releasing 0.12.1 without the fix would make 0.12.0 and 0.12.1 basically
crippled (have to ask users to avoid bulkinsert with row-writing)
Therefore RC1 will be canceled and I'll start preparing for RC2.