brew upgrade nmap
Updating Homebrew...
==> Auto-updated Homebrew!
Updated 1 tap (homebrew/core).
No changes to formulae.
Error: nmap not installed

nmap --version
Nmap version 6.40-2 ( http://nmap.org )
Platform: x86_64-apple-darwin10.8.0
Compiled with: liblua-5.2.2 openssl-0.9.7l nmap-libpcre-7.6 nmap-libpcap-1.2.1 nmap-libdnet-1.12 ipv6
Compiled without:
Available nsock engines: kqueue poll select

brew info nmap
nmap: stable 7.60 (bottled), HEAD
Port scanning utility for large networks
https://nmap.org/
Conflicts with:
  ndiff (because both install ndiff