Libvirt: Fix error message when unable to preallocate image
Libvirt: Fix error message when unable to preallocate image

For this error message,

LOG.error(_LE('Unable to preallocate_images=%(imgs)s at path: '
              '%(path)s'), {'imgs': CONF.preallocate_images,
                            'path': self.path})

CONF.preallocate_images can only be set to 'none' and 'space'
so if error message come out, it would be

Unable to preallocate_images=none(or space) at path: /path/to/image.
which is not correct.

Change-Id: Id122a5e1ad1d0441d6b75d081b2be3f276439a2a

zhimin711/nova,LoHChina/nova,joker946/nova,phenoxim/nova,Tehsmash/nova,petrutlucian94/nova,tealover/nova,raildo/nova,iuliat/nova,shail2810/nova,vmturbo/nova,alvarolopez/nova,mahak/nova,CloudServer/nova,gooddata/openstack-nova,devendermishrajio/nova_test_latest,TwinkleChawla/nova,bgxavier/nova,hanlind/nova,akash1808/nova_test_latest,nikesh-mahalka/nova,Juniper/nova,jianghuaw/nova,mahak/nova,dims/nova,tudorvio/nova,jeffrey4l/nova,CloudServer/nova,sebrandon1/nova,bigswitch/nova,eonpatapon/nova,felixma/nova,cloudbase/nova,double12gzh/nova,TwinkleChawla/nova,klmitch/nova,JianyuWang/nova,rahulunair/nova,rajalokan/nova,mmnelemane/nova,zzicewind/nova,yatinkumbhare/openstack-nova,isyippee/nova,JioCloud/nova,alaski/nova,mahak/nova,dims/nova,thomasem/nova,Tehsmash/nova,devendermishrajio/nova,devendermishrajio/nova_test_latest,shail2810/nova,j-carpentier/nova,nikesh-mahalka/nova,zaina/nova,Stavitsky/nova,phenoxim/nova,gooddata/openstack-nova,barnsnake351/nova,felixma/nova,ruslanloman/nova,adelina-t/nova,akash1808/nova,yosshy/nova,petrutlucian94/nova,belmiromoreira/nova,tangfeixiong/nova,MountainWei/nova,klmitch/nova,whitepages/nova,akash1808/nova_test_latest,LoHChina/nova,jianghuaw/nova,fnordahl/nova,bigswitch/nova,yatinkumbhare/openstack-nova,noironetworks/nova,jianghuaw/nova,fnordahl/nova,klmitch/nova,tangfeixiong/nova,rajalokan/nova,Francis-Liu/animated-broccoli,belmiromoreira/nova,cyx1231st/nova,NeCTAR-RC/nova,yosshy/nova,kimjaejoong/nova,vmturbo/nova,gooddata/openstack-nova,cyx1231st/nova,vmturbo/nova,Juniper/nova,mikalstill/nova,zaina/nova,Stavitsky/nova,sebrandon1/nova,apporc/nova,mmnelemane/nova,watonyweng/nova,ted-gould/nova,eonpatapon/nova,cernops/nova,scripnichenko/nova,BeyondTheClouds/nova,barnsnake351/nova,CCI-MOC/nova,cloudbase/nova,cernops/nova,rajalokan/nova,rahulunair/nova,CEG-FYP-OpenStack/scheduler,mandeepdhami/nova,isyippee/nova,akash1808/nova,jeffrey4l/nova,tudorvio/nova,rahulunair/nova,alaski/nova,MountainWei/nova,raildo/nova,bgxavier/nova,mandeepdhami/nova,Juniper/nova,openstack/nova,BeyondTheClouds/nova,cloudbase/nova,rajalokan/nova,adelina-t/nova,whitepages/nova,watonyweng/nova,ruslanloman/nova,JioCloud/nova_test_latest,klmitch/nova,sebrandon1/nova,cernops/nova,zhimin711/nova,double12gzh/nova,takeshineshiro/nova,openstack/nova,apporc/nova,joker946/nova,iuliat/nova,varunarya10/nova_test_latest,hanlind/nova,CCI-MOC/nova,NeCTAR-RC/nova,edulramirez/nova,tealover/nova,noironetworks/nova,takeshineshiro/nova,Francis-Liu/animated-broccoli,scripnichenko/nova,CEG-FYP-OpenStack/scheduler,zzicewind/nova,JianyuWang/nova,JioCloud/nova,devendermishrajio/nova,mikalstill/nova,mikalstill/nova,gooddata/openstack-nova,vmturbo/nova,JioCloud/nova_test_latest,j-carpentier/nova,hanlind/nova,BeyondTheClouds/nova,ted-gould/nova,openstack/nova,varunarya10/nova_test_latest,edulramirez/nova,thomasem/nova,kimjaejoong/nova,Juniper/nova,alvarolopez/nova,jianghuaw/nova