[MERGE] trees - add get_parent_ids

[Robert Collins]

This patch adds a get_parent_ids() call to all our tree objects (at
least, I think to all of them ;)).

This call returns:
[] for a tree with unknown parents
['null:'] for a tree descending from null:
[revid, ...] in general.

EmptyTree descends from ['null:'].
RevisionTree mirrors the revision graph.
WorkingTree provides the union of last_revision and pending merges.

-Rob

-- 
GPG key available at: <http://www.robertcollins.net/keys.txt>.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: tree-get-parent-ids.patch
Type: text/x-patch
Size: 11732 bytes
Desc: not available
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20060616/7fd97e52/attachment.bin 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 191 bytes
Desc: This is a digitally signed message part
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20060616/7fd97e52/attachment.pgp