BlockPolicy, ExcuseFinder: refer to DISTRO-release

On Ubuntu we want this to say ubuntu-release, on Debian debian-release.
Substitute the first part with the name of the distro.

britney2/excusefinder.py

@@ -61,7 +61,8 @@ class ExcuseFinder(object):
             excuse.add_verdict_info(
                 excuse.policy_verdict,
                 "Not touching package, as requested by %s "
-                "(contact debian-release if update is needed)" % hint.user)
+                "(contact %s-release if update is needed)" % (hint.user,
+                                                              self.options.distribution))
             excuse.addreason("block")
             self.excuses[excuse.name] = excuse
             return False
@@ -585,7 +586,8 @@ class ExcuseFinder(object):
                 excuse.add_verdict_info(
                     excuse.policy_verdict,
                     "Not removing package, due to block hint by %s "
-                    "(contact debian-release if update is needed)" % blockhint.user)
+                    "(contact %s-release if update is needed)" % (blockhint.user,
+                                                                  self.options.distribution))
                 excuse.addreason("block")
                 blocked = True
 

britney2/policies/policy.py

@@ -1318,7 +1318,7 @@ class BlockPolicy(BasePolicy):
             else:
                 verdict = PolicyVerdict.REJECTED_NEEDS_APPROVAL
                 if is_primary or block_cmd == 'block-udeb':
-                    tooltip = "please contact debian-release if update is needed"
+                    tooltip = "please contact %s-release if update is needed" % self._britney.options.distribution
                     # redirect people to d-i RM for udeb things:
                     if block_cmd == 'block-udeb':
                         tooltip = "please contact the d-i release manager if an update is needed"