svn-apply should support adding empty files. This report is also related to changing the executable bit -- since changing only the executable bit will result in a diff with no "contents".
See here for an example: https://bugs.webkit.org/show_bug.cgi?id=38693#c4
See Bug 27204 or Bug 39409 for adding support for the executable bit. *** This bug has been marked as a duplicate of bug 29684 ***