BUG #5680: Failure to start: too many private dirs demanded

The following bug has been logged online:

Bug reference: 5680
Logged by: Alexey Parshin
Email address: alexeyp(at)gmail(dot)com
PostgreSQL version: 9.0.0
Operating system: Gentoo Linux
Description: Failure to start: too many private dirs demanded
Details:

PostgreSQL (fresh install) fails to start.
The only message in the log file says:
FATAL: too many private dirs demanded

strace pg_ctl start -D/var/lib/postgresql/9.0/data shows (tail):

read(3, "# Locale name alias data base.\n#"..., 4096) = 2570
read(3, "", 4096) = 0
close(3) = 0
munmap(0xb77e4000, 4096) = 0
open("/usr/lib/postgresql-9.0/share/locale/en_AU.UTF-8/LC_MESSAGES/pg_ctl-9.
0.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/postgresql-9.0/share/locale/en_AU.utf8/LC_MESSAGES/pg_ctl-9.0
.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/postgresql-9.0/share/locale/en_AU/LC_MESSAGES/pg_ctl-9.0.mo",
O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/postgresql-9.0/share/locale/en.UTF-8/LC_MESSAGES/pg_ctl-9.0.m
o", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/postgresql-9.0/share/locale/en.utf8/LC_MESSAGES/pg_ctl-9.0.mo
", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/postgresql-9.0/share/locale/en/LC_MESSAGES/pg_ctl-9.0.mo",
O_RDONLY) = -1 ENOENT (No such file or directory)
fstat64(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0), ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0xb77e4000
write(1, "server starting\n", 16server starting
) = 16
exit_group(0) = ?
FATAL: too many private dirs demanded