zsh completion for "svn" is obsolete

[Yann Ollivier <technical@yann-ollivier.org>]

Hello,

The completion functions for "svn" seem to be broken since subversion 1.7. 
For instance if you hit "svn add <TAB>", it will complete all files in the 
current directory, while it used to complete only those files not under 
subversion control. Likewise, if you hit "svn remove <TAB>" it used to 
complete all files under subversion control, but now returns only 
subdirectories (or all files if there are no subdirectories).

This affects at least zsh 5.0.0 and 5.0.2.

The reason is: the helper functions in
zsh/functions/Completion/Unix/_subversion
are obsolete. They all rely on the presence of ".svn" subdirectories in 
all directories under version control, whereas since subversion 1.7 these 
directories have been removed and the list of versioned files is 
maintained as a database in $HOME/.svn

A related issue has been discussed and fixed in the past 
(completion after hitting "svn <TAB>"), but this one seems to be still 
unresolved.

Thanks!

             Yann Ollivier