[dev] undefined function: realpath()

[Lance Wilson]

I just updated my horde version from HEAD on CVS and I get this error 
whenever I try to update any of the configurations:  The interface seems to 
be functioning normally although.

Fatal error: Call to undefined function: realpath() in 
/home/webhome/vmail/horde/admin/setup/config.php on line 62

Could somebody tell me what this error means?  I'm guessing that during the 
update process it did not download a library of some type?