Fix issue with pip installing oslo.config-1.2.0
Fix issue with pip installing oslo.config-1.2.0

Fixes bug #1194807

Firstly, we update the oslo.config dep to 1.2.0a3 because of the issue
with namespace packages (bug #1194742).

But the main issue here is that when we previously depended on 1.2.0a3
we found that if you did:

  $> pip install -r nova/requirements.txt

then you end up with the oslo.config 1.1.1 code installed. This is
because oslo.config>=1.1.0 gets pulled in as a transitive dep and pip
gets confused.

See I977700d73342e81ee962019b76238d2cb2b1fff4

You can reproduce with e.g.

  $> pip install \
       http://.../oslo.config-1.2.0a3.tar.gz#egg=oslo.config-1.2.0a3 \
       python-keystoneclient
  $> pip freeze | grep oslo.config
  oslo.config-1.2.0a3
  $> python -c 'from oslo.config.cfg import DeprecatedOpt'
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
  ImportError: cannot import name DeprecatedOpt

This is because of a bug with pip where it sees oslo.config-1.2.0a3 and
oslo.config as two unrelated things. It should strip the version part of
the egg= fragment before using it as a package name, but it doesn't.

However, we can simply use the -f/--find-links pip option in our
requirements.txt to add the tarball URL to the list of URLs considered
and also add the oslo.config>=1.2.0a3 dependency:

  $> pip install \
       -f http://.../oslo.config-1.2.0a3.tar.gz#egg=oslo.config-1.2.0a3 \
       'oslo.config>=1.2.0a3' \
       python-keystoneclient
  $> pip freeze | grep oslo.config
  oslo.config-1.2.0a3
  $> python -c 'from oslo.config.cfg import DeprecatedOpt'

This is actually exactly the semantics we want and we go to great
lengths in pbr to get these semantics while using a single tarball URL.
The only downside to this --find-links strategy is that we gain an extra
line in our requirements.txt ... but it does work around the pip bug.

Change-Id: I6f3eb5fd2c75615d9a1cae172aed859b36b27d4c

cernops/nova,alexandrucoman/vbox-nova-driver,CloudServer/nova,jeffrey4l/nova,alaski/nova,JioCloud/nova,eonpatapon/nova,edulramirez/nova,eharney/nova,tanglei528/nova,adelina-t/nova,CiscoSystems/nova,takeshineshiro/nova,whitepages/nova,Francis-Liu/animated-broccoli,mandeepdhami/nova,OpenAcademy-OpenStack/nova-scheduler,Yusuke1987/openstack_template,mgagne/nova,cloudbase/nova,affo/nova,rajalokan/nova,joker946/nova,ntt-sic/nova,bigswitch/nova,sacharya/nova,belmiromoreira/nova,redhat-openstack/nova,barnsnake351/nova,rajalokan/nova,viggates/nova,scripnichenko/nova,dawnpower/nova,mmnelemane/nova,NeCTAR-RC/nova,gooddata/openstack-nova,sebrandon1/nova,orbitfp7/nova,whitepages/nova,jeffrey4l/nova,JioCloud/nova_test_latest,felixma/nova,alvarolopez/nova,imsplitbit/nova,zaina/nova,cloudbase/nova,silenceli/nova,zhimin711/nova,gooddata/openstack-nova,LoHChina/nova,alaski/nova,openstack/nova,Brocade-OpenSource/OpenStack-DNRM-Nova,BeyondTheClouds/nova,silenceli/nova,Yusuke1987/openstack_template,shahar-stratoscale/nova,cloudbase/nova-virtualbox,vladikr/nova_drafts,alexandrucoman/vbox-nova-driver,rajalokan/nova,vladikr/nova_drafts,SUSE-Cloud/nova,TwinkleChawla/nova,NeCTAR-RC/nova,barnsnake351/nova,scripnichenko/nova,ntt-sic/nova,shail2810/nova,mahak/nova,projectcalico/calico-nova,rajalokan/nova,apporc/nova,yatinkumbhare/openstack-nova,phenoxim/nova,adelina-t/nova,klmitch/nova,double12gzh/nova,dims/nova,virtualopensystems/nova,edulramirez/nova,zaina/nova,mikalstill/nova,maelnor/nova,rahulunair/nova,akash1808/nova,orbitfp7/nova,mandeepdhami/nova,devendermishrajio/nova_test_latest,belmiromoreira/nova,mgagne/nova,jianghuaw/nova,tianweizhang/nova,hanlind/nova,noironetworks/nova,cloudbau/nova,Stavitsky/nova,mikalstill/nova,alvarolopez/nova,leilihh/nova,thomasem/nova,cloudbau/nova,vmturbo/nova,eonpatapon/nova,badock/nova,rahulunair/nova,shahar-stratoscale/nova,devendermishrajio/nova,vmturbo/nova,viggates/nova,tangfeixiong/nova,Juniper/nova,leilihh/novaha,isyippee/nova,iuliat/nova,iuliat/nova,fnordahl/nova,rickerc/nova_audit,imsplitbit/nova,citrix-openstack-build/nova,raildo/nova,affo/nova,rickerc/nova_audit,j-carpentier/nova,eayunstack/nova,sebrandon1/nova,mahak/nova,redhat-openstack/nova,tudorvio/nova,vmturbo/nova,OpenAcademy-OpenStack/nova-scheduler,TwinkleChawla/nova,berrange/nova,BeyondTheClouds/nova,leilihh/nova,Tehsmash/nova,tealover/nova,apporc/nova,hanlind/nova,blueboxgroup/nova,klmitch/nova,varunarya10/nova_test_latest,jianghuaw/nova,TieWei/nova,hanlind/nova,dims/nova,watonyweng/nova,luogangyi/bcec-nova,LoHChina/nova,BeyondTheClouds/nova,JianyuWang/nova,rahulunair/nova,joker946/nova,j-carpentier/nova,Brocade-OpenSource/OpenStack-DNRM-Nova,nikesh-mahalka/nova,gooddata/openstack-nova,devendermishrajio/nova_test_latest,ted-gould/nova,petrutlucian94/nova_dev,plumgrid/plumgrid-nova,openstack/nova,isyippee/nova,Juniper/nova,bgxavier/nova,klmitch/nova,zzicewind/nova,CEG-FYP-OpenStack/scheduler,varunarya10/nova_test_latest,maelnor/nova,CCI-MOC/nova,phenoxim/nova,spring-week-topos/nova-week,felixma/nova,MountainWei/nova,Metaswitch/calico-nova,tangfeixiong/nova,watonyweng/nova,petrutlucian94/nova,cyx1231st/nova,projectcalico/calico-nova,zhimin711/nova,SUSE-Cloud/nova,rrader/nova-docker-plugin,petrutlucian94/nova_dev,qwefi/nova,kimjaejoong/nova,cernops/nova,fnordahl/nova,jianghuaw/nova,ruslanloman/nova,angdraug/nova,thomasem/nova,saleemjaveds/https-github.com-openstack-nova,akash1808/nova_test_latest,jianghuaw/nova,eayunstack/nova,JioCloud/nova,tealover/nova,ewindisch/nova,CiscoSystems/nova,spring-week-topos/nova-week,tianweizhang/nova,saleemjaveds/https-github.com-openstack-nova,yosshy/nova,Yuriy-Leonov/nova,TieWei/nova,Juniper/nova,devendermishrajio/nova,ewindisch/nova,badock/nova,bigswitch/nova,Juniper/nova,ruslanloman/nova,gooddata/openstack-nova,rrader/nova-docker-plugin,CCI-MOC/nova,tudorvio/nova,CloudServer/nova,double12gzh/nova,leilihh/novaha,bgxavier/nova,yosshy/nova,sebrandon1/nova,nikesh-mahalka/nova,bclau/nova,zzicewind/nova,takeshineshiro/nova,Yuriy-Leonov/nova,qwefi/nova,mahak/nova,plumgrid/plumgrid-nova,sacharya/nova,openstack/nova,noironetworks/nova,eharney/nova,klmitch/nova,angdraug/nova,devoid/nova,cloudbase/nova-virtualbox,Stavitsky/nova,CEG-FYP-OpenStack/scheduler,dawnpower/nova,yatinkumbhare/openstack-nova,cloudbase/nova,blueboxgroup/nova,shail2810/nova,kimjaejoong/nova,devoid/nova,tanglei528/nova,virtualopensystems/nova,citrix-openstack-build/nova,ted-gould/nova,cernops/nova,Metaswitch/calico-nova,petrutlucian94/nova,vmturbo/nova,bclau/nova,berrange/nova,JianyuWang/nova,akash1808/nova,Tehsmash/nova,mmnelemane/nova,cyx1231st/nova,mikalstill/nova,akash1808/nova_test_latest,Francis-Liu/animated-broccoli,MountainWei/nova,raildo/nova,JioCloud/nova_test_latest,luogangyi/bcec-nova