This is an upstream patch, see:
    <http://www.zsh.org/mla/workers/2011/msg00177.html>

Index: pkg-zsh/Functions/VCS_Info/Backends/VCS_INFO_detect_svn
===================================================================
--- pkg-zsh.orig/Functions/VCS_Info/Backends/VCS_INFO_detect_svn	2011-02-20 13:14:58.000000000 +0100
+++ pkg-zsh/Functions/VCS_Info/Backends/VCS_INFO_detect_svn	2011-02-20 13:15:10.000000000 +0100
@@ -7,5 +7,5 @@
 [[ $1 == '--flavours' ]] && return 1
 
 VCS_INFO_check_com ${vcs_comm[cmd]} || return 1
-[[ -d ".svn" ]] && return 0
+{ [[ -f ".svn/entries" ]] || [[ -f ".svn/format" ]] } && return 0
 return 1