Change the built-in default socket directory to be /var/run/postgresql.
For backwards compatibility with (probably non-libpq-based) clients that
might still expect to find the socket in /tmp, also create a socket in
/tmp.  This is to resolve communication problems with clients operating
under systemd's PrivateTmp environment, which won't be using the same
global /tmp directory as the server; see bug #825448.

Note that we apply the socket directory change at the level of the
hard-wired defaults in the C code, not by just twiddling the setting in
postgresql.conf.sample; this is so that the change will take effect on
server package update, without requiring any existing postgresql.conf
to be updated.  (Of course, a user who dislikes this behavior can still
override it via postgresql.conf.)

This patch must be applied after postgresql-multi-sockets.patch, at
least until 9.3 when that will be part of the upstream package.

diff --git a/contrib/pg_upgrade/test.sh b/contrib/pg_upgrade/test.sh
index d44c599..845b417 100644
--- a/contrib/pg_upgrade/test.sh
+++ b/contrib/pg_upgrade/test.sh
@@ -121,6 +121,12 @@ logdir=$PWD/log
 rm -rf "$logdir"
 mkdir "$logdir"
 
+# we want the Unix sockets in $temp_root
+PGHOST=$temp_root
+export PGHOST
+
+POSTMASTER_OPTS="$POSTMASTER_OPTS -c unix_socket_directories='$PGHOST'"
+
 # enable echo so the user can see what is being executed
 set -x
 
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 1428cb6..3613732 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2901,7 +2901,7 @@ static struct config_string ConfigureNamesString[] =
 		},
 		&Unix_socket_directories,
 #ifdef HAVE_UNIX_SOCKETS
-		DEFAULT_PGSOCKET_DIR,
+		DEFAULT_PGSOCKET_DIR ", /tmp",
 #else
 		"",
 #endif
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 452ac0b..ce6ca96 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1015,7 +1015,7 @@ setup_config(void)
 
 #ifdef HAVE_UNIX_SOCKETS
 	snprintf(repltok, sizeof(repltok), "#unix_socket_directories = '%s'",
-			 DEFAULT_PGSOCKET_DIR);
+			 DEFAULT_PGSOCKET_DIR ", /tmp");
 #else
 	snprintf(repltok, sizeof(repltok), "#unix_socket_directories = ''");
 #endif
diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h
index ee7dab0..f3e3ed9 100644
--- a/src/include/pg_config_manual.h
+++ b/src/include/pg_config_manual.h
@@ -144,7 +144,7 @@
  * here's where to twiddle it.  You can also override this at runtime
  * with the postmaster's -k switch.
  */
-#define DEFAULT_PGSOCKET_DIR  "/tmp"
+#define DEFAULT_PGSOCKET_DIR  "/var/run/postgresql"
 
 /*
  * The random() function is expected to yield values between 0 and