[PATCH 3/5] Basic support for keeping a ref to the parent branch.

[Yann Dirson <ydirson@altern.org>]

This adds a framework to handle the parent branch of a stack, in
addition to the parent remote, and to set them when creating a stack.

Signed-off-by: Yann Dirson <ydirson@altern.org>
---

 TODO           |    2 --
 stgit/stack.py |   27 ++++++++++++++++++++++++++-
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/TODO b/TODO
index 549bc9d..884b831 100644
--- a/TODO
+++ b/TODO
@@ -20,8 +20,6 @@ The future, when time allows or if someone else does them:
 - multiple heads in a patch - useful for forking a patch,
   synchronising with other patches (diff format or in other
   repositories)
-- "pull" argument should default to a sane value, "origin" is wrong in
-  many cases
 - commit directly to a patch which is not top
 - patch synchronisation between between branches (as some people,
   including me have the same patches based on different branches and
diff --git a/stgit/stack.py b/stgit/stack.py
index e801f42..9d4f881 100644
--- a/stgit/stack.py
+++ b/stgit/stack.py
@@ -410,6 +410,29 @@ class Series(StgitObject):
             config.add_section(section)
         config.set(section, 'remote', remote)
 
+    def get_parent_branch(self):
+        section = 'branch "%s"' % self.__name
+        if config.has_option(section, 'merge'):
+            return config.get(section, 'merge')
+        elif rev_parse('heads/origin'):
+            return 'heads/origin'
+        else:
+            raise StackException, 'Cannot find a parent branch for "%s"' % self.__name
+
+    def __set_parent_branch(self, name):
+        section = 'branch "%s"' % self.__name
+        if not config.has_section(section):
+            config.add_section(section)
+        config.set(section, 'merge', name)
+
+    def set_parent(self, remote, localbranch):
+        if localbranch:
+            self.__set_parent_branch(localbranch)
+            if remote:
+                self.__set_parent_remote(remote)
+        elif remote:
+            raise StackException, 'Remote "%s" without a branch cannot be used as parent' % remote
+
     def __patch_is_current(self, patch):
         return patch.get_name() == self.get_current()
 
@@ -458,7 +481,7 @@ class Series(StgitObject):
         """
         return os.path.isdir(self.__patch_dir)
 
-    def init(self, create_at=False):
+    def init(self, create_at=False, parent_remote=None, parent_branch=None):
         """Initialises the stgit series
         """
         bases_dir = os.path.join(self.__base_dir, 'refs', 'bases')
@@ -475,6 +498,8 @@ class Series(StgitObject):
 
         os.makedirs(self.__patch_dir)
 
+        self.set_parent(parent_remote, parent_branch)
+        
         create_dirs(bases_dir)
 
         self.create_empty_field('applied')