Update the SVN mirror branches

svn-trunk-mirror must remain identical to "trunk" in SVN

git checkout -b svn-trunk-mirror origin/svn-trunk-mirror

Pull any outstanding SVN commits into the mirror branch

git svn rebase

Push the new SVN commits to origin (e.g. GitHub)

git push origin svn-trunk-mirror

Continuous integration branches have minimal modifications to enable

building and testing on automated CI systems, e.g. travis, AppVeyor

Rebase the trunk CI build scripts

git checkout svn-trunk-ci git rebase svn-trunk-mirror

Verify the build

Push to GitHub

git push origin svn-trunk-mirror