We merge changes from time to time from trunk to our current branches. We use SVN 1.7.6 and tried it with SmartSVN and Tortoise SVN.
It does not work to merge the changes made in the svn:externals property (new externals, raised fixed revisions of externals) in the trunk to the branch. It just does not merge the changes but completely ignores them.
However, when reintegrating changes in svn:externals from branch to trunk it works.
The problem can only be solved by doing a second merge after the first merge with property "Ignore ancestry" set to true and only choosing the revision range that was merged with the first merge.
But in our opinion a normal merge from trunk to branch should also merge changes within the svn:externals property or are we on the wrong tack?
Once the trunk is merged into branch, the branch needs to be updated again in order to update externals. So update the branch after merge. It will fetch all the changes made in externals.