1.2 install problems

[dcharno]

I've tried installing version 1.2 on two Ubuntu machines.  In both 
cases, the version is listed as "unknown".  What am I doing wrong in the 
source installation?

# md5sum mercurial-1.2.tar.gz
ac9d16b078f99f7a89d6865421570f05  mercurial-1.2.tar.gz

# make install PREFIX=/usr
.
.
.
# hg --version
Mercurial Distributed SCM (version unknown)

Copyright (C) 2005-2008 Matt Mackall <mpm at selenic.com> and others
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.