Additional Notes About the Merge Operation

Sub-tree Merges

It is recommended to perform a merge on the whole working copy (select its root directory when triggering the operation) to avoid sub-tree mergeinfo. Sub-tree mergeinfo is the mergeinfo recorded to describe a sub-tree merge. That is, a merge done directly to a child of a branch root that might be needed in certain situations. There is nothing special about sub-tree merges or sub-tree mergeinfo except that the complete record of merges to a branch may not be contained solely in the mergeinfo on the branch root and you may have to look to any sub-tree mergeinfo to get a full accounting. Fortunately, Subversion does this for you and rarely will you need to look for it.

Merging from Foreign Repositories

Subversion supports merging from foreign repositories. While all merge source URLs must point to the same repository, the merge target (from the working copy) may come from a different repository than the sources. However, copies made in the merge source will be transformed into plain additions in the merge target. Also, merge-tracking is not supported for merges from foreign repositories.
Note: When performing merges from repositories other than the one corresponding to the target item (from the working copy), the Ignore ancestry / Disable merge tracking option, in the Merge Options wizard page, will be enabled automatically (and you cannot change this).

General Merge Recommendations

As a recommendation, you should only merge into clean working copies that do not contain any of the following:
Important: This recommendation becomes mandatory when performing a reintegrate merge operation. Also, trying to merge to mixed-revision working copies will fail in all types of merge operations.
Remember: The merge result is only in your local working copy and needs to be committed to the repository for it to be available to others.