Fix default value for reason trail
Fix default value for reason trail

The default value for the reason trail field used to be ht.EmptyList in
2.9 but was incorrectly changed to None in 2.10. This patch corrects
this error which fixes a bug in batch creation of instances.

Signed-off-by: Thomas Thrainer <98bdeac947eb8ca18146e9ce7f092788ec242cd1@google.com>
Reviewed-by: Jose A. Lopes <0fb9c4f8511df4ec2ae28af879e9d462f6218a2c@google.com>

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