Add test case for local-only packages pinned to never

Test from the fix for the regression in trusty for LP #1821308.

test/integration/test-policy-pinning

@@ -407,7 +407,20 @@ testsuccessequal "coolstuff:
         500 file:${tmppath}/aptarchive stable/main all Packages" aptcache policy coolstuff
 
 
-
+msgmsg "Check that local-only versions can be pinned correctly (LP: #1821308)"
+echo "Package: coolstuff
+Pin: version 2.0~bpo1
+Pin-Priority: 1000" > rootdir/etc/apt/preferences
+testsuccessequal "coolstuff:
+  Installed: 2.0~bpo1
+  Candidate: 2.0~bpo1
+  Version table:
+     2.0~bpo2 100
+        100 file:${tmppath}/aptarchive backports/main all Packages
+ *** 2.0~bpo1 1000
+        100 ${tmppath}/rootdir/var/lib/dpkg/status
+     1.0 500
+        500 file:${tmppath}/aptarchive stable/main all Packages" aptcache policy coolstuff
 
 # Check for 0
 echo "Package: coolstuff