=== modified file 'lib/lp/code/browser/branch.py'
--- lib/lp/code/browser/branch.py	2011-02-17 03:29:50 +0000
+++ lib/lp/code/browser/branch.py	2011-02-25 02:46:55 +0000
@@ -339,10 +339,7 @@
         return Link('+register-merge', text, icon='add', enabled=enabled)

     def link_bug(self):
-        if self.context.linked_bugs:
-            text = 'Link to another bug report'
-        else:
-            text = 'Link to a bug report'
+        text = 'Link a bug report'
         return Link('+linkbug', text, icon='add')

     def link_blueprint(self):
@@ -604,12 +601,11 @@
     @cachedproperty
     def linked_bugs(self):
         """Return a list of DecoratedBugs linked to the branch."""
-        bugs = self.context.linked_bugs
         if self.context.is_series_branch:
-            bugs = [
-                bug for bug in bugs
-                if bug.bugtask.status in UNRESOLVED_BUGTASK_STATUSES]
-        return bugs
+            status_filter = UNRESOLVED_BUGTASK_STATUSES
+        else:
+            status_filter = None
+        return list(self.context.getLinkedBugsAndTasks(status_filter)

     @cachedproperty
     def revision_info(self):

=== modified file 'lib/lp/code/browser/decorations.py'
--- lib/lp/code/browser/decorations.py	2010-08-24 10:45:57 +0000
+++ lib/lp/code/browser/decorations.py	2011-02-25 02:50:42 +0000
@@ -100,6 +100,8 @@
         tasks, we get them all at once, and provide decorated bugs (that have
         their tasks cached).
         """
+        # To whomever it may concern, this function should be pushed down to
+        # the model, and the related visibility checks made part of the query.
         bugs = defaultdict(list)
         for bug, task in self.branch.getLinkedBugsAndTasks():
             bugs[bug].append(task)

=== modified file 'lib/lp/code/browser/tests/test_branch.py'
--- lib/lp/code/browser/tests/test_branch.py	2011-02-25 02:08:52 +0000
+++ lib/lp/code/browser/tests/test_branch.py	2011-02-25 02:38:32 +0000
@@ -19,6 +19,7 @@
 from canonical.config import config
 from canonical.database.constants import UTC_NOW
 from canonical.launchpad.helpers import truncate_text
+from canonical.launchpad.webapp.publisher import canonical_url
 from canonical.launchpad.webapp.servers import LaunchpadTestRequest
 from canonical.testing.layers import (
     DatabaseFunctionalLayer,
@@ -29,8 +30,6 @@
     find_tag_by_id,
     setupBrowser,
     )
-from canonical.launchpad.webapp.publisher import canonical_url
-
 from lp.app.interfaces.headings import IRootContext
 from lp.bugs.interfaces.bugtask import (
     BugTaskStatus,
@@ -58,6 +57,7 @@
     person_logged_in,
     TestCaseWithFactory,
     )
+from lp.testing.matchers import BrowsesWithQueryLimit
 from lp.testing.views import create_initialized_view


@@ -361,6 +361,41 @@
             self.assertTrue(
                 bug.bugtask.status in UNRESOLVED_BUGTASK_STATUSES)

+    def test_linked_bugs_nonseries_branch_query_scaling(self):
+        # As we add linked bugs, the query count for a branch index page stays
+        # constant.
+        branch = self.factory.makeAnyBranch()
+        browses_under_limit = BrowsesWithQueryLimit(54, branch.owner)
+        # Start with some bugs, otherwise we might see a spurious increase
+        # depending on optimisations in eager loaders.
+        with person_logged_in(branch.owner):
+            self._addBugLinks(branch)
+            self.assertThat(branch, browses_under_limit)
+        with person_logged_in(branch.owner):
+            # Add plenty of bugs.
+            for _ in range(5):
+                self._addBugLinks(branch)
+            self.assertThat(branch, browses_under_limit)
+
+    def test_linked_bugs_series_branch_query_scaling(self):
+        # As we add linked bugs, the query count for a branch index page stays
+        # constant.
+        product = self.factory.makeProduct()
+        branch = self.factory.makeProductBranch(product=product)
+        browses_under_limit = BrowsesWithQueryLimit(54, branch.owner)
+        with person_logged_in(product.owner):
+            product.development_focus.branch = branch
+        # Start with some bugs, otherwise we might see a spurious increase
+        # depending on optimisations in eager loaders.
+        with person_logged_in(branch.owner):
+            self._addBugLinks(branch)
+            self.assertThat(branch, browses_under_limit)
+        with person_logged_in(branch.owner):
+            # Add plenty of bugs.
+            for _ in range(5):
+                self._addBugLinks(branch)
+            self.assertThat(branch, browses_under_limit)
+
     def _add_revisions(self, branch, nr_revisions=1):
         revisions = []
         for seq in range(1, nr_revisions+1):

=== modified file 'lib/lp/code/interfaces/branch.py'
--- lib/lp/code/interfaces/branch.py	2011-02-04 16:34:12 +0000
+++ lib/lp/code/interfaces/branch.py	2011-02-25 02:44:09 +0000
@@ -409,8 +409,12 @@
         readonly=True,
         value_type=Reference(schema=Interface))) # Really IBug

-    def getLinkedBugsAndTasks():
-        """Return a result set for the bugs with their tasks."""
+    def getLinkedBugsAndTasks(status_filter):
+        """Return a result set for the bugs with their tasks.
+
+        :param status_filter: If none, return all linked bugs. For any other
+            value, passed onto the bug search as a constraint.
+        """

     @call_with(registrant=REQUEST_USER)
     @operation_parameters(

=== modified file 'lib/lp/code/model/branch.py'
--- lib/lp/code/model/branch.py	2011-01-25 18:59:18 +0000
+++ lib/lp/code/model/branch.py	2011-02-25 02:44:20 +0000
@@ -302,8 +302,8 @@
         'Bug', joinColumn='branch', otherColumn='bug',
         intermediateTable='BugBranch', orderBy='id')

-    def getLinkedBugsAndTasks(self):
-        """Return a result set for the bugs with their tasks."""
+    def getLinkedBugsAndTasks(self, status_filter):
+        """See `IBranch`."""
         from lp.bugs.model.bug import Bug
         from lp.bugs.model.bugbranch import BugBranch
         from lp.bugs.model.bugtask import BugTask