What you are doing here is that you merge the changes from svn / trunk into your git function branch, and then dcommit these changes into the svn equivalent of your function branch. This means that you have a branch in both git and svn, which doesn’t make much sense to me if you work on it alone.
, , svn/trunk . git, trunk, svn dcommit , . ( .)
, , :
git svn fetch
git checkout -b my_branch svn/trunk
...work...commit...work...commit...
git svn fetch && git rebase svn/trunk
...see if it still works
git svn dcommit # commits all of this to svn trunk