libvirt: increase min required libvirt to 1.2.1

As advertized during Mitaka, increase the min required
libvirt version to 1.2.1.

At this time there is no new "next" version planned.
The need to advertize a version increase for Ocata
will be decided later.

Change-Id: Ib73cfbd9fc01114ac513730d182ed127710a9e5d

nova/tests/unit/virt/libvirt/fakelibvirt.py

@@ -150,8 +150,8 @@ VIR_SECRET_USAGE_TYPE_VOLUME = 1
 VIR_SECRET_USAGE_TYPE_CEPH = 2
 VIR_SECRET_USAGE_TYPE_ISCSI = 3
 
-# Libvirt version
-FAKE_LIBVIRT_VERSION = 10002
+# Libvirt version to match MIN_LIBVIRT_VERSION in driver.py
+FAKE_LIBVIRT_VERSION = 1002001
 
 
 class HostInfo(object):

nova/virt/libvirt/driver.py

@@ -394,7 +394,7 @@ patch_tpool_proxy()
 # versions. Over time, this will become a common min version
 # for all architectures/hypervisors, as this value rises to
 # meet them.
-MIN_LIBVIRT_VERSION = (0, 10, 2)
+MIN_LIBVIRT_VERSION = (1, 2, 1)
 # TODO(berrange): Re-evaluate this at start of each release cycle
 # to decide if we want to plan a future min version bump.
 # MIN_LIBVIRT_VERSION can be updated to match this after

releasenotes/notes/min-required-libvirt-b948948949669b02.yaml

@@ -0,0 +1,4 @@
+---
+upgrade:
+  - The minimum required version of libvirt has been
+    increased to 1.2.1