Yet another issue with pg_upgrade vs unix_socket_directories

I went back for another try at building the Fedora packages with 9.2
branch tip ... and it still failed at pg_upgrade's "make check".
The reason for this is that test.sh starts a couple of random
postmasters, and those postmasters expect to put their sockets in
the configured default location (which is now /var/run/postgresql
on Fedora), and that's not there in a minimal build environment.

I hacked it up with the attached quick-and-dirty patch, but I wonder
if anyone's got a better idea.

            regards, tom lane

diff --git a/contrib/pg_upgrade/test.sh b/contrib/pg_upgrade/test.sh
index 31e30af..c00aa98 100644
*** a/contrib/pg_upgrade/test.sh
--- b/contrib/pg_upgrade/test.sh
*************** logdir=$PWD/log
*** 60,69 ****
  rm -rf "$logdir"
  mkdir "$logdir"

  set -x

  $oldbindir/initdb
! $oldbindir/pg_ctl start -l "$logdir/postmaster1.log" -w
  if "$MAKE" -C "$oldsrc" installcheck; then
      pg_dumpall >"$temp_root"/dump1.sql || pg_dumpall1_status=$?
      if [ "$newsrc" != "$oldsrc" ]; then
--- 60,73 ----
  rm -rf "$logdir"
  mkdir "$logdir"

+ # we want the Unix sockets in $temp_root
+ PGHOST=$temp_root
+ export PGHOST
+
  set -x

  $oldbindir/initdb
! $oldbindir/pg_ctl start -l "$logdir/postmaster1.log" -o "-c unix_socket_directories='$PGHOST'" -w
  if "$MAKE" -C "$oldsrc" installcheck; then
      pg_dumpall >"$temp_root"/dump1.sql || pg_dumpall1_status=$?
      if [ "$newsrc" != "$oldsrc" ]; then
*************** initdb
*** 106,112 ****

  pg_upgrade -d "${PGDATA}.old" -D "${PGDATA}" -b "$oldbindir" -B "$bindir"

! pg_ctl start -l "$logdir/postmaster2.log" -w
  sh ./analyze_new_cluster.sh
  pg_dumpall >"$temp_root"/dump2.sql || pg_dumpall2_status=$?
  pg_ctl -m fast stop
--- 110,116 ----

  pg_upgrade -d "${PGDATA}.old" -D "${PGDATA}" -b "$oldbindir" -B "$bindir"

! pg_ctl start -l "$logdir/postmaster2.log" -o "-c unix_socket_directories='$PGHOST'" -w
  sh ./analyze_new_cluster.sh
  pg_dumpall >"$temp_root"/dump2.sql || pg_dumpall2_status=$?
  pg_ctl -m fast stop