How To merge trunk changes to branch
cd to branch working directory
find the revision the branch was created if this is the first merge
svn log --stop-on-copy http://svn.symfony-project.com/branches/yourbranch
find the revision of the last merge if this is not the first merge
svn log --stop-on-copy http://svn.symfony-project.com/branches/yourbranch | grep -B3 merge
with revision number from previous step, and the latest trunk revision number, merge changes to your branch
svn merge -r<previous_step_number>:<latest_trunk_revision> http://svn.symfony-project.com/trunk .
fix conflicts if any
check in updates from trunk to your branch. record revision number of merge to assist when it needs to be done again.
svn commit -m 'user: merge trunk changes to my branch revs <previous_step_number>:<latest_trunk_revision>'