Merge lp:~maxb/bzr-builddeb/graph-heads-misuse into lp:bzr-builddeb

[Max Bowsher]

Via some weirdness in the rxtx UDD import (mentioned in bug 785859), I discovered some code which assumes that:

   len(graph.heads([A, B])) == 1

means that it is safe to pull A into a branch currently at B.

This, however, fails to take into account whether A is an ancestor of B, or B is an ancestor of A.

The end result was that the importer elided the Ubuntu-specific history from the oneiric branch after a ./requeue_package.py --full, pulling the Debian revision corresponding to a synced package version into the Ubuntu branch.

The fix is simply to take account of *which* of A and B is the head.

[James Westby (james-w)]

review: Approve

[James Westby (james-w)]

Nice catch Max, thanks.

James

=== modified file 'import_dsc.py'
--- import_dsc.py	2011-04-29 12:54:58 +0000
+++ import_dsc.py	2011-06-03 07:57:30 +0000
@@ -572,9 +572,8 @@
                     try:
                         graph = branch.branch.repository.get_graph(
                                 self.branch.repository)
-                        other_revid = branch.revid_of_version(version)
-                        if len(graph.heads([other_revid,
-                                    self.branch.last_revision()])) == 1:
+                        if graph.is_ancestor(self.branch.last_revision(),
+                                branch.revid_of_version(version)):
                             return branch
                     finally:
                         branch.branch.unlock()
@@ -585,9 +584,8 @@
                     try:
                         graph = branch.branch.repository.get_graph(
                                 self.branch.repository)
-                        other_revid = branch.revid_of_version(version)
-                        if len(graph.heads([other_revid,
-                                    self.branch.last_revision()])) == 1:
+                        if graph.is_ancestor(self.branch.last_revision(),
+                                branch.revid_of_version(version)):
                             return branch
                     finally:
                         branch.branch.unlock()
@@ -622,31 +620,27 @@
         try:
             for branch in reversed(self.get_lesser_branches()):
                 if branch.has_upstream_version(version, md5=md5):
-                    # Check for divergenge.
+                    # Check that they haven't diverged
                     other_up_branch = branch.upstream_branch
                     other_up_branch.lock_read()
                     try:
                         graph = other_up_branch.repository.get_graph(
                                 up_branch.repository)
-                        other_revid = branch.revid_of_upstream_version(
-                                version)
-                        if len(graph.heads([other_revid,
-                                    up_branch.last_revision()])) == 1:
+                        if graph.is_ancestor(up_branch.last_revision(),
+                                branch.revid_of_upstream_version(version)):
                             return branch
                     finally:
                         other_up_branch.unlock()
             for branch in self.get_greater_branches():
                 if branch.has_upstream_version(version, md5=md5):
-                    # Check for divergenge.
+                    # Check that they haven't diverged
                     other_up_branch = branch.upstream_branch
                     other_up_branch.lock_read()
                     try:
                         graph = other_up_branch.repository.get_graph(
                                 up_branch.repository)
-                        other_revid = branch.revid_of_upstream_version(
-                                version)
-                        if len(graph.heads([other_revid,
-                                    up_branch.last_revision()])) == 1:
+                        if graph.is_ancestor(up_branch.last_revision(),
+                                branch.revid_of_upstream_version(version)):
                             return branch
                     finally:
                         other_up_branch.unlock()