Fix for: connection to database failed: Unix-domain socket path "/build/buildd-postgresql-9.3_9.3~beta1-1-i386-mHjRUH/postgresql-9.3-9.3~beta1/build/contrib/pg_upgrade/.s.PGSQL.50432" is too long (maximum 107 bytes)

See also: http://lists.debian.org/debian-wb-team/2013/05/msg00015.html

--- a/src/bin/pg_upgrade/option.c
+++ b/src/bin/pg_upgrade/option.c
@@ -460,6 +460,11 @@ get_sock_dir(ClusterInfo *cluster, bool
 			cluster->sockdir = pg_malloc(MAXPGPATH);
 			if (!getcwd(cluster->sockdir, MAXPGPATH))
 				pg_fatal("could not determine current directory\n");
+#ifndef UNIX_PATH_MAX
+#define UNIX_PATH_MAX 108
+#endif
+			if (strlen(cluster->sockdir) >= UNIX_PATH_MAX - sizeof(".s.PGSQL.50432"))
+				strcpy(cluster->sockdir, "/tmp"); /* fall back to tmp */
 		}
 		else
 		{