Fix repair handoff crash, missing not sent fun

/cc @jrwest @javajolt 
Partition repair was crashing on an undefined 'not sent function' in the handoff accumulator record. Jordan should know the details of the recent change that introduced him. Jordan: please review, feel free to replace with cleaner version of the fix.

Without this fix, the partition_repair riak_test fails every time. It passes with the fix.