Can happen that you have commited something wrong into your Subversion repositoy and you want to set your Head revision to a specific revision.
The following steps will illustrate how can you change it.
- Checkout your repository
svn checkout http://url
- move to your working copy folder
cd folder
- do a reverse merge (i'm reverting to revision 1269)
svn merge -r HEAD:1269 .
- now that youry working copy is set to rv 1269, you need to commit to update the repository
svn commit -m "set head revision to r 1269"
That's it. Now your head revision will reflect the r 1269.