In Committer's Guide - SVN Primer [1] (5.4.3.5 Merging), the instruction and example show that one should merge to the specific directory instead of / in a branch. However, I've heard that this might not be the case any more since 10-RELEASE (need verification). [1]: https://www.freebsd.org/doc/en_US.ISO8859-1/articles/committers-guide/article.html#subversion-primer
Closing this issue since we are moving to Git.