Reapply commit 2a6de57a after merge

In the last merge I erroneously discarded the changes introduced by
commit 2a6de57a "Check the results of master IP RPCs". This commit
reintroduces them.

Signed-off-by: Andrea Spadaccini <spadaccio@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>