git-svn: branch: avoid systematic prompt for cert/pass
git-svn: branch: avoid systematic prompt for cert/pass

Commands such as "git svn init/fetch/dcommit" do not prompt for client
certificate/password if they are stored in SVN config file.  Make
"git svn branch" consistent with the other commands, as SVN::Client is
capable of building its own authentication baton from information in the
SVN config directory.

Signed-off-by: Monard Vong <b81fed1e7d8f81e660b1558a8221f14572c28428@gmail.com>
Signed-off-by: Eric Wong <8c2951295f8292b0c03727bc4652981172298eae@yhbt.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git