[UPHPU] Can I switch to Subversion midstream?

[Richard K Miller]

I'd like to upgrade my MediaWiki installation to version 1.8, which  
just came out yesterday, and I thought now would be a good time to  
start using Subversion.  (I wasn't using Subversion before.)

When I tried checking out the latest version, it choked on the  
existing files:

$ svn co http://svn.wikimedia.org/svnroot/mediawiki/branches/REL1_8/ 
phase3 .
svn: Failed to add directory 'maintenance': object of the same name  
already exists

Can I force Subversion to override this error and replace the  
existing files?

Richard