SVN how to resolve new tree conflicts when file is added on two branches

Question

When merging a couple of branches (using SVN 1.6.1) where a file has been added on both branches (and then worked on in those separate branches) I'm getting one of the new tree conflicts:

      C foo.txt
  >   local obstruction, incoming add upon merge

I need the changes from both branches, but the tree conflict doesn't give me the usual .working, .merge-left & .merge-right files -- which is understandable due to the nature of the conflict. There are quite a few of these conflict, and ones where a delete of the same file has occurred on each branch, but they're simple to resolve.

How can I resolve this issue? The SVN redbean book (for 1.6) doesn't cover this situation.

Answer 1

As mentioned in the "Tree Conflict" design document:

XFAIL conflict from merge of add over versioned file

This test does a merge which brings a file addition without history onto an existing versioned file.
This should be a tree conflict on the file of the 'local obstruction, incoming add upon merge' variety. Fixed expectations in r35341.

(This is also called "evil twins" in ClearCase by the way):
a file is created twice (here "added" twice) in two different branches, creating two different histories for two different elements, but with the same name.

The theoretical solution is to manually merge those files (with an external diff tool) in the destination branch 'B2'.

If you still are working on the source branch, the ideal scenario would be to remove that file from the source branch B1, merge back from B2 to B1 in order to make that file visible on B1 (you will then work on the same element).
If a merge back is not possible because merges only occurs from B1 to B2, then a manual merge will be necessary for each B1->B2 merges.

Answer 2

I found a post suggesting a solution for that. It's about to run:

svn resolve --accept working

which will claim the local version files as OK.
You can run it for single file or entire project catalogues.