Because of the objectify cache, after the first "read, change, write" of the
first mutation - the second mutation would "read" the original value, which
would then fail to be written with the error "Entity changed since init()".
This was specifically seen in the "UpdateRegistrarCommand", but likely affected
other commands as well.
Clearing the cache before each command solves this issue.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=192328213
3dfd141e0f