RHEL 8.0 build

Hi,

 Trying to set up a buildfarm animal on a RHEL 8.0 (beta) system,
the build fails early:

$ ./run_build.pl --nosend --nostatus --verbose
Sat Nov 24 20:09:28 2018: buildfarm run for CHANGEME:HEAD starting
CHANGEME:HEAD          [20:09:28] checking out source ...
CHANGEME:HEAD          [20:09:33] checking if build run needed ...
CHANGEME:HEAD          [20:09:34] copying source to pgsql.build ...
CHANGEME:HEAD          [20:09:35] running configure ...
Branch: HEAD
Stage Configure failed with status 1
$

It appears to be a "configure" script looking for python; and there is
no such.  You can have python3 or python2 - but neither package install
provides a symlink of just "python".


Obviously I could get going by manually adding one, but perhaps
other people would benefit from a neater fix.
-- 
Cheers,
  Jeremy