Use python-hawkey instead of rpm-python.

The advantages are that the hawkey API is consistent between python
versions, and that it is a bit cleaner for this purpose.

python-hawkey adds two new dependencies above what rpm-python adds, but it
is required by dnf anyway, so it will likely be installed by most users.

Now raise an AvailabilityError if the number of packages is not exactly
equal to 1. This is more correct and is not going to cause more stack
traces, because the error is caught in the method that calls
packageVersion.

Signed-off-by: mulhern <amulhern@redhat.com>

blivet/tasks/availability.py

@@ -21,8 +21,7 @@
 
 import abc
 from distutils.version import LooseVersion
-import rpm
-import six
+import hawkey
 
 from six import add_metaclass
 
@@ -136,19 +135,19 @@ def __init__(self, package=None):
 
     @property
     def packageVersion(self):
-        """ Returns the version of the package.
+        """ Returns the version of the installed package.
 
             :returns: the package version
             :rtype: LooseVersion
+            :raises AvailabilityError: on failure to obtain package version
         """
-        ts = rpm.TransactionSet()
-        info = ts.dbMatch("provides", self.package.package_name)
-        if len(info) == 0:
+        sack = hawkey.Sack()
+        sack.load_system_repo()
+        query = hawkey.Query(sack).filter(name=self.package.package_name, latest=True)
+        packages = query.run()
+        if len(packages) != 1:
             raise AvailabilityError("Could not determine package version for %s" % self.package.package_name)
-        version = next(info)['version']
-        if six.PY3:
-            version = version.decode()
-        return LooseVersion(version)
+        return LooseVersion(packages[0].version)
 
     def availabilityErrors(self, resource):
         if self._availabilityErrors is not None and CACHE_AVAILABILITY:

python-blivet.spec

@@ -43,7 +43,7 @@ Requires: libselinux-python
 Requires: libblockdev >= %{libblockdevver}
 Requires: libblockdev-plugins-all >= %{libblockdevver}
 Requires: libselinux-python
-Requires: rpm-python
+Requires: python-hawkey
 
 %description
 The python-blivet package is a python module for examining and modifying
@@ -65,7 +65,7 @@ Requires: util-linux >= %{utillinuxver}
 Requires: dosfstools
 Requires: e2fsprogs >= %{e2fsver}
 Requires: lsof
-Requires: rpm-python3
+Requires: python3-hawkey
 
 %description -n python3-%{realname}
 The python3-%{realname} is a python3 package for examining and modifying storage