(Mark or Bruce?) It fixes a problem when cpp gives a warning when
precompiling /dev/null like:  "/dev/null", line 1: 1506-229 (W)
File is empty.  This leads to a hangup when doing the description
load during initdb, since stderr also ends up in the global1.description
and local1_template1.description

stderr has to be redirected to /dev/null:

Andreas Zeugswetter