If deriving SVN_SSH from GIT_SSH on msys, also add quotes
In contrast to GIT_SSH, SVN_SSH requires quotes for paths that contain spaces. As GIT_SSH will not work if it contains quotes, it is safe to assume it never contains quotes. Also, adding quotes to SVN_SSH for paths that do not contain spaces does no harm. So we always add quotes when deriving SVN_SSH from GIT_SSH on msys.