init-repository: fix checkout of pure git repositories

Since some projects are maintained in git repositories only even the
'svn' DEPS file has some git shasums instead of svn revisions.
Check the current shasum and tag outside of the ref block so we actually
end up checking out the parsed shasum for non-git-svn repositories.

Change-Id: Iabc4a5b15e50a0f0df84179a65929352ee2addb7
Reviewed-by: Michael Bruning <michael.bruning@digia.com>