baserlib: Accept empty body in FillOpcode
baserlib: Accept empty body in FillOpcode

Signed-off-by: Michael Hanselmann <68b67885ff74281219b4a4be33cc20fd45078d7c@google.com>
Reviewed-by: René Nussbaumer <rn@google.com>
(cherry picked from commit c6e1a3eef05674d637570c39f25a799cec7ba187)

Signed-off-by: Michael Hanselmann <68b67885ff74281219b4a4be33cc20fd45078d7c@google.com>

andir/ganeti,leshchevds/ganeti,dimara/ganeti,mbakke/ganeti,apyrgio/snf-ganeti,grnet/snf-ganeti,onponomarev/ganeti,leshchevds/ganeti,mbakke/ganeti,yiannist/ganeti,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,bitemyapp/ganeti,ganeti-github-testing/ganeti-test-1,grnet/snf-ganeti,andir/ganeti,mbakke/ganeti,leshchevds/ganeti,onponomarev/ganeti,ganeti/ganeti,apyrgio/ganeti,apyrgio/ganeti,ganeti/ganeti,ganeti/ganeti,dimara/ganeti,andir/ganeti,apyrgio/snf-ganeti,bitemyapp/ganeti,yiannist/ganeti